/* ═══════════════════════════════════════════
   PyLab — styles.css
   ═══════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:ital,wght@0,400;0,500;0,600;1,400&family=IBM+Plex+Sans:wght@400;500;600&display=swap');

/* ── THEME VARIABLES ─────────────────────── */
:root {
  --bg:         #0e0e0e;
  --surface:    #141414;
  --surface2:   #1a1a1a;
  --surface3:   #202020;
  --border:     #262626;
  --border2:    #333333;
  --text:       #d8d8d8;
  --text-dim:   #888888;
  --text-faint: #444444;

  --easy:   #4ade80;
  --medium: #facc15;
  --hard:   #f87171;
  --expert: #c084fc;
  --accent: #60a5fa;

  --font-sans: 'IBM Plex Sans', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  --r:  3px;
  --r2: 6px;
  --t:  120ms ease;

  --sidebar-w: 256px;
  --header-h:  50px;
  --term-h:    220px;

  /* Mobile touch target minimum */
  --touch-min: 44px;
}

/* ── LIGHT MODE ──────────────────────────── */
@media (prefers-color-scheme: light) {
  :root {
    --bg:         #f5f5f5;
    --surface:    #ffffff;
    --surface2:   #f0f0f0;
    --surface3:   #e8e8e8;
    --border:     #dedede;
    --border2:    #c8c8c8;
    --text:       #1a1a1a;
    --text-dim:   #555555;
    --text-faint: #aaaaaa;
    --easy:   #16a34a;
    --medium: #ca8a04;
    --hard:   #dc2626;
    --expert: #9333ea;
    --accent: #2563eb;
  }
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; overflow: hidden; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 14px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

button { cursor: pointer; font-family: inherit; }
input  { font-family: inherit; }
pre, textarea, code { font-family: var(--font-mono); }

/* Focus visible — keyboard accessibility */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
button:focus:not(:focus-visible),
input:focus:not(:focus-visible) { outline: none; }

/* ── BOOT SCREEN ─────────────────────────── */
.boot-screen {
  position: fixed; inset: 0; z-index: 9000;
  background: var(--bg);
  display: flex; align-items: center; justify-content: center;
  transition: opacity 400ms ease;
}
.boot-screen.hidden { opacity: 0; pointer-events: none; }
.boot-inner {
  display: flex; flex-direction: column;
  align-items: center; gap: 14px; width: 200px;
}
.boot-logo {
  width: 56px; height: 56px;
  border: 1px solid var(--border2); border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: var(--text-dim); font-size: 24px;
  opacity: 0;
  animation: boot-fade-up 400ms ease 50ms forwards;
}
.boot-name {
  font-family: var(--font-mono); font-size: 22px;
  font-weight: 600; color: var(--text); letter-spacing: -0.04em;
  opacity: 0;
  animation: boot-fade-up 400ms ease 200ms forwards;
}
.boot-bar-wrap {
  width: 100%; height: 2px;
  background: var(--surface3); border-radius: 2px; overflow: hidden;
  opacity: 0;
  animation: boot-fade-up 400ms ease 350ms forwards;
}
.boot-bar {
  height: 100%; width: 0; border-radius: 2px;
  background: var(--accent);
  transition: width 300ms ease;
}
.boot-status {
  font-size: 10px; color: var(--text-faint);
  font-family: var(--font-mono); letter-spacing: 0.04em;
  opacity: 0;
  animation: boot-fade-up 400ms ease 450ms forwards;
}
@keyframes boot-fade-up {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── PROGRESS BAR ────────────────────────── */
#progress-bar {
  position: fixed; top: 0; left: 0;
  height: 2px; width: 0;
  background: var(--accent);
  transition: width 280ms ease;
  z-index: 9999;
}

/* ── HEADER ─────────────────────────────── */
header {
  position: fixed; top: 0; left: 0; right: 0;
  z-index: 200; height: var(--header-h);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center;
  justify-content: space-between;
  padding: 0 12px;
}
.header-left {
  display: flex; align-items: center; gap: 8px;
}
.hamburger {
  display: none;
  background: transparent; border: 1px solid var(--border);
  border-radius: var(--r); width: 34px; height: 34px;
  align-items: center; justify-content: center;
  color: var(--text-faint); font-size: 13px;
  transition: all var(--t); flex-shrink: 0;
}
.hamburger:hover { color: var(--text-dim); border-color: var(--border2); background: var(--surface2); }
.logo {
  display: flex; align-items: center; gap: 7px;
  font-family: var(--font-mono); font-size: 14px;
  font-weight: 600; color: var(--text); letter-spacing: -0.02em;
  user-select: none;
}
.logo i { color: var(--text-faint); font-size: 12px; }
.header-right { display: flex; align-items: center; gap: 6px; }
.hbadge {
  font-family: var(--font-mono); font-size: 10px;
  color: var(--text-faint); padding: 3px 8px;
  border: 1px solid var(--border); border-radius: var(--r);
  letter-spacing: 0.04em; display: inline-flex; align-items: center; gap: 5px;
}
.hbadge i { font-size: 10px; }
.pyodide-status { cursor: default; }
.pyodide-status.ready { color: var(--easy); border-color: rgba(74,222,128,0.3); }
.pyodide-status.error { color: var(--hard); border-color: rgba(248,113,113,0.3); }
.hbadge-commit {
  text-decoration: none; transition: all var(--t);
}
.hbadge-commit:hover { color: var(--text-dim); border-color: var(--border2); }
#commit-badge, #changelog-btn, .hbadge-gh { display: none; }
.hbadge-btn {
  background: transparent; cursor: pointer; transition: all var(--t);
}
.hbadge-btn:hover { color: var(--text-dim); border-color: var(--border2); background: var(--surface2); }
.hbadge-btn.active { color: var(--accent); border-color: rgba(96,165,250,0.4); background: rgba(96,165,250,0.07); }
.hbadge-signin {
  background: rgba(96,165,250,0.1); color: var(--accent);
  border-color: rgba(96,165,250,0.35); cursor: pointer;
  transition: all var(--t);
}
.hbadge-signin:hover { background: rgba(96,165,250,0.18); border-color: var(--accent); }

/* ── CHANGELOG PANEL ─────────────────────── */
.cl-backdrop {
  position: fixed; inset: 0; z-index: 399;
  background: rgba(0,0,0,0.45);
  opacity: 0; pointer-events: none;
  transition: opacity 200ms ease;
}
.cl-backdrop.open { opacity: 1; pointer-events: all; }
.cl-panel {
  position: fixed; top: 0; right: 0; bottom: 0;
  width: min(480px, 100vw);
  background: var(--surface); border-left: 1px solid var(--border);
  z-index: 400; display: flex; flex-direction: column;
  transform: translateX(100%);
  transition: transform 240ms cubic-bezier(.4,0,.2,1);
  box-shadow: -8px 0 32px rgba(0,0,0,0.35);
}
.cl-panel.open { transform: translateX(0); }
.cl-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 14px; border-bottom: 1px solid var(--border);
  flex-shrink: 0; background: var(--surface);
}
.cl-title {
  display: flex; align-items: center; gap: 8px;
  font-family: var(--font-mono); font-size: 13px; font-weight: 600;
  color: var(--text);
}
.cl-title i { color: var(--accent); }
.cl-header-right { display: flex; align-items: center; gap: 8px; }
.cl-gh-link {
  color: var(--text-faint); font-size: 15px;
  text-decoration: none; transition: color var(--t);
  display: flex; align-items: center;
}
.cl-gh-link:hover { color: var(--text); }
.cl-close {
  background: transparent; border: none; color: var(--text-faint);
  font-size: 15px; padding: 4px; cursor: pointer;
  transition: color var(--t); display: flex; align-items: center;
}
.cl-close:hover { color: var(--text); }
.cl-body {
  overflow-y: auto; flex: 1; padding: 0;
}
.cl-body::-webkit-scrollbar { width: 3px; }
.cl-body::-webkit-scrollbar-thumb { background: var(--border2); }
.cl-loading, .cl-error {
  display: flex; align-items: center; justify-content: center;
  gap: 8px; padding: 32px 16px;
  color: var(--text-faint); font-size: 13px;
}
.cl-error { color: var(--hard); }

/* Markdown render area */
.cl-md { font-size: 13px; color: var(--text); line-height: 1.7; padding: 16px; }
.cl-md h1 { font-size: 17px; font-weight: 700; color: var(--text); margin: 0 0 8px; line-height: 1.3; }
.cl-md h2 { font-size: 15px; font-weight: 600; color: var(--text); margin: 10px 0 6px; line-height: 1.3; }
.cl-md h3 { font-size: 13px; font-weight: 600; color: var(--text-dim); margin: 8px 0 4px; }
.cl-md p  { margin: 0 0 6px; }
.cl-md hr { border: none; border-top: 1px solid var(--border2); margin: 10px 0; }
.cl-md strong { font-weight: 600; color: var(--text); }
.cl-md em { font-style: italic; color: var(--text-dim); }
.cl-md code {
  font-family: var(--font-mono); font-size: 11px;
  background: var(--surface3); border: 1px solid var(--border);
  border-radius: 3px; padding: 1px 5px; color: var(--accent);
}
.cl-md pre {
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: var(--r); padding: 10px 12px; overflow-x: auto;
  margin: 6px 0;
}
.cl-md pre code {
  background: none; border: none; padding: 0;
  font-size: 11px; color: var(--text-dim);
}
.cl-md ul, .cl-md ol {
  margin: 4px 0 6px 18px; padding: 0;
}
.cl-md li { margin-bottom: 2px; }
.cl-md blockquote {
  border-left: 3px solid var(--border2); margin: 6px 0;
  padding: 4px 10px; color: var(--text-dim);
}

/* ── CHANGELOG PANEL ─────────────────────── */
.changelog-backdrop {
  position: fixed; inset: 0; z-index: 399;
  background: transparent;
}
.changelog-panel {
  position: fixed; top: calc(var(--header-h) + 6px); right: 10px;
  width: 360px; max-height: calc(100vh - var(--header-h) - 20px);
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r2); z-index: 400;
  display: flex; flex-direction: column;
  box-shadow: 0 8px 32px rgba(0,0,0,0.4);
  transform: translateY(-6px); opacity: 0; pointer-events: none;
  transition: transform 200ms ease, opacity 160ms ease;
}
.changelog-panel.open {
  transform: translateY(0); opacity: 1; pointer-events: all;
}
.changelog-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 12px; border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}
.changelog-title {
  display: flex; align-items: center; gap: 7px;
  font-family: var(--font-mono); font-size: 12px;
  font-weight: 600; color: var(--text);
}
.changelog-title i { color: var(--accent); font-size: 11px; }
.changelog-gh-link {
  color: var(--text-faint); font-size: 13px; margin-left: 2px;
  transition: color var(--t); text-decoration: none;
}
.changelog-gh-link:hover { color: var(--text); }
.changelog-close {
  background: transparent; border: none;
  color: var(--text-faint); font-size: 13px;
  padding: 4px; transition: color var(--t);
  display: flex; align-items: center; justify-content: center;
}
.changelog-close:hover { color: var(--text); }
.changelog-body {
  overflow-y: auto; flex: 1; padding: 6px 0;
}
.changelog-body::-webkit-scrollbar { width: 2px; }
.changelog-body::-webkit-scrollbar-thumb { background: var(--border2); }
.changelog-loading {
  display: flex; align-items: center; justify-content: center;
  gap: 8px; padding: 24px; color: var(--text-faint); font-size: 12px;
}
.changelog-error {
  padding: 16px 14px; color: var(--hard); font-size: 12px;
  display: flex; align-items: center; gap: 7px;
}
.commit-item {
  padding: 8px 12px; border-bottom: 1px solid var(--border);
  transition: background var(--t);
}
.commit-item:last-child { border-bottom: none; }
.commit-item:hover { background: var(--surface2); }
.commit-top {
  display: flex; align-items: baseline; gap: 6px; margin-bottom: 3px;
}
.commit-num {
  font-family: var(--font-mono); font-size: 9px;
  color: var(--text-faint); flex-shrink: 0;
}
.commit-sha {
  font-family: var(--font-mono); font-size: 9px;
  color: var(--accent); text-decoration: none; flex-shrink: 0;
}
.commit-sha:hover { text-decoration: underline; }
.commit-msg {
  font-size: 12px; color: var(--text);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
  flex: 1; min-width: 0;
}
.commit-bottom {
  display: flex; align-items: center; gap: 8px;
}
.commit-author {
  font-size: 10px; color: var(--text-faint);
  display: flex; align-items: center; gap: 4px;
}
.commit-author i { font-size: 8px; }
.commit-date {
  font-size: 10px; color: var(--text-faint);
  margin-left: auto;
}

/* ── LAYOUT ─────────────────────────────── */
.app {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  height: 100vh;
  padding-top: var(--header-h);
}

/* ── SIDEBAR ────────────────────────────── */
.sidebar-overlay {
  display: none;
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 150;
  backdrop-filter: blur(2px);
  -webkit-backdrop-filter: blur(2px);
}
.sidebar {
  border-right: 1px solid var(--border);
  display: flex; flex-direction: column;
  overflow: hidden; background: var(--surface);
  transition: transform 250ms ease;
}
.sidebar-top {
  padding: 10px; border-bottom: 1px solid var(--border);
  display: flex; flex-direction: column; gap: 7px; flex-shrink: 0;
}
.sidebar-header {
  display: flex; align-items: center; justify-content: space-between;
}
.sidebar-label {
  font-size: 9px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.12em;
  color: var(--text-faint); padding: 0 2px;
  display: flex; align-items: center; gap: 5px;
}
.sidebar-label i { font-size: 9px; }
.sidebar-close {
  display: none;
  background: transparent; border: none;
  color: var(--text-faint); font-size: 14px;
  padding: 6px; transition: color var(--t);
  min-width: 32px; min-height: 32px;
  align-items: center; justify-content: center;
}
.sidebar-close:hover { color: var(--text-dim); }

.search-wrap { position: relative; }
.search-wrap > i {
  position: absolute; left: 9px; top: 50%;
  transform: translateY(-50%); color: var(--text-faint);
  font-size: 11px; pointer-events: none;
}
#search-input {
  width: 100%; background: var(--surface2);
  border: 1px solid var(--border); border-radius: var(--r);
  padding: 8px 28px 8px 28px;
  color: var(--text); font-size: 13px; outline: none;
  transition: border-color var(--t);
  /* Prevent iOS zoom on focus */
  font-size: max(16px, 13px);
}
@media (min-width: 769px) {
  #search-input { font-size: 12px; padding: 6px 28px 6px 26px; }
}
#search-input:focus { border-color: var(--accent); }
#search-input::placeholder { color: var(--text-faint); }
.search-clear {
  position: absolute; right: 7px; top: 50%; transform: translateY(-50%);
  background: transparent; border: none; color: var(--text-faint);
  font-size: 11px; padding: 4px; cursor: pointer; transition: color var(--t);
  min-width: 28px; min-height: 28px;
  display: flex; align-items: center; justify-content: center;
}
.search-clear:hover { color: var(--text-dim); }

.filter-bar {
  display: flex; align-items: center; gap: 5px;
}
.filter-btn {
  flex: 1; display: flex; align-items: center; gap: 6px;
  padding: 6px 10px; background: var(--surface2);
  border: 1px solid var(--border); border-radius: var(--r);
  color: var(--text-dim); font-size: 11px; font-weight: 500;
  transition: all var(--t);
}
.filter-btn:hover { border-color: var(--border2); color: var(--text); }
.filter-btn.active { border-color: var(--accent); color: var(--accent); background: rgba(96,165,250,0.07); }
.filter-btn i { font-size: 11px; }
.filter-badge {
  margin-left: auto;
  background: var(--accent); color: #000;
  font-size: 9px; font-weight: 700;
  min-width: 16px; height: 16px; border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  padding: 0 4px;
}
.filter-clear-btn {
  width: 28px; height: 28px; display: flex; align-items: center; justify-content: center;
  background: transparent; border: 1px solid var(--border); border-radius: var(--r);
  color: var(--text-faint); font-size: 11px; flex-shrink: 0;
  transition: all var(--t);
}
.filter-clear-btn:hover { color: var(--hard); border-color: rgba(248,113,113,0.4); background: rgba(248,113,113,0.07); }

/* Filter dropdown panel */
.filter-panel {
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: var(--r2); overflow: hidden;
  max-height: 0; opacity: 0; pointer-events: none;
  transition: max-height 220ms ease, opacity 180ms ease;
  display: flex; flex-direction: column;
}
.filter-panel.open { max-height: 400px; opacity: 1; pointer-events: all; }
.filter-section {
  padding: 10px 10px 8px;
  border-bottom: 1px solid var(--border);
}
.filter-section:last-child { border-bottom: none; }
.filter-section-label {
  font-size: 9px; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.1em; color: var(--text-faint); margin-bottom: 7px;
}
.filter-chips { display: flex; flex-wrap: wrap; gap: 4px; }
.fchip {
  padding: 4px 10px; background: transparent;
  border: 1px solid var(--border); border-radius: 20px;
  color: var(--text-faint); font-size: 11px; font-weight: 500;
  cursor: pointer; transition: all var(--t); white-space: nowrap;
}
.fchip:hover { color: var(--text-dim); border-color: var(--border2); }
.fchip-all.active    { background: var(--surface3); color: var(--text); border-color: var(--border2); }
.fchip-easy.active   { color: var(--easy);   border-color: var(--easy);   background: rgba(74,222,128,0.08); }
.fchip-medium.active { color: var(--medium); border-color: var(--medium); background: rgba(250,204,21,0.08); }
.fchip-hard.active   { color: var(--hard);   border-color: var(--hard);   background: rgba(248,113,113,0.08); }
.fchip-expert.active { color: var(--expert); border-color: var(--expert); background: rgba(192,132,252,0.08); }
.fchip-topic.active  { color: var(--accent); border-color: var(--accent); background: rgba(96,165,250,0.08); }

/* ── SKELETON LOADING ───────────────────── */
@keyframes skel-shimmer {
  0%   { background-position: -200% 0; }
  100% { background-position:  200% 0; }
}
.skel {
  background: linear-gradient(90deg,
    var(--surface2) 25%, var(--surface3) 50%, var(--surface2) 75%
  );
  background-size: 200% 100%;
  animation: skel-shimmer 1.4s ease infinite;
  border-radius: var(--r);
}
.proj-skeleton {
  display: flex; align-items: center; gap: 7px;
  padding: 8px 7px; margin-bottom: 1px; min-height: 48px;
}
.proj-skeleton .skel-num  { width: 20px; height: 10px; flex-shrink: 0; }
.proj-skeleton .skel-body { flex: 1; display: flex; flex-direction: column; gap: 5px; }
.proj-skeleton .skel-name { height: 11px; width: 70%; }
.proj-skeleton .skel-meta { height: 8px; width: 35%; }

.project-list { overflow-y: auto; flex: 1; padding: 5px; }
.project-list::-webkit-scrollbar { width: 2px; }
.project-list::-webkit-scrollbar-thumb { background: var(--border2); }

.proj-item {
  display: flex; align-items: center; gap: 7px;
  padding: 8px 7px; border-radius: var(--r);
  cursor: pointer; border: 1px solid transparent;
  transition: all var(--t); margin-bottom: 1px;
  min-height: 48px; /* accessibility touch target */
}
.proj-item:hover  { background: var(--surface2); }
.proj-item.active { background: var(--surface2); border-color: var(--border2); }
.proj-item:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }
.proj-num {
  font-family: var(--font-mono); font-size: 9px;
  color: var(--text-faint); min-width: 20px; flex-shrink: 0;
}
.proj-body { flex: 1; min-width: 0; }
.proj-name {
  font-size: 12px; font-weight: 500; color: var(--text-dim);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
  transition: color var(--t);
}
.proj-item.active .proj-name,
.proj-item:hover  .proj-name { color: var(--text); }
.proj-meta { display: flex; align-items: center; gap: 4px; margin-top: 2px; }
.diff-dot { width: 5px; height: 5px; border-radius: 50%; flex-shrink: 0; }
.dot-easy   { background: var(--easy); }
.dot-medium { background: var(--medium); }
.dot-hard   { background: var(--hard); }
.dot-expert { background: var(--expert); }
.diff-text { font-family: var(--font-mono); font-size: 9px; letter-spacing: 0.04em; }
.text-easy   { color: var(--easy); }
.text-medium { color: var(--medium); }
.text-hard   { color: var(--hard); }
.text-expert { color: var(--expert); }
.solved-icon { font-size: 9px; color: var(--easy); flex-shrink: 0; }

/* Sidebar footer */
.sidebar-footer {
  padding: 8px 10px;
  border-top: 1px solid var(--border);
  flex-shrink: 0;
}
.btn-reset-progress {
  width: 100%; background: transparent;
  border: 1px solid var(--border); border-radius: var(--r);
  color: var(--text-faint); font-size: 9px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.06em;
  padding: 7px 0; display: flex; align-items: center;
  justify-content: center; gap: 5px; transition: all var(--t);
  min-height: 34px;
}
.btn-reset-progress:hover { color: var(--hard); border-color: rgba(248,113,113,0.3); background: rgba(248,113,113,0.05); }
.btn-reset-progress i { font-size: 9px; }

/* ── MAIN ───────────────────────────────── */
.main-panel { display: flex; flex-direction: column; overflow: hidden; background: var(--bg); }

/* ── WELCOME ─────────────────────────────── */
.welcome {
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  height: 100%; gap: 20px; padding: 2rem; text-align: center;
  animation: rise 250ms ease;
  overflow-y: auto;
}
@keyframes rise {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
.welcome-mark {
  width: 48px; height: 48px;
  border: 1px solid var(--border2); border-radius: var(--r2);
  display: flex; align-items: center; justify-content: center;
  color: var(--text-dim); font-size: 20px;
}
.welcome h1 {
  font-family: var(--font-mono); font-size: 32px;
  font-weight: 600; color: var(--text); letter-spacing: -0.04em;
}
.welcome p { font-size: 13px; color: var(--text-dim); max-width: 380px; line-height: 1.8; }
.stats-row {
  display: flex; align-items: stretch;
  border: 1px solid var(--border); border-radius: var(--r); overflow: hidden;
}
.stat-cell {
  padding: 10px 18px;
  border-right: 1px solid var(--border);
  display: flex; flex-direction: column; align-items: center; gap: 2px;
}
.stat-cell:last-child { border-right: none; }
.stat-num { font-family: var(--font-mono); font-size: 17px; font-weight: 600; line-height: 1; }
.stat-lbl { font-size: 9px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--text-faint); }
.welcome-actions { display: flex; gap: 8px; flex-wrap: wrap; justify-content: center; }
.welcome-btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 10px 20px; background: var(--surface2);
  border: 1px solid var(--border2); border-radius: var(--r);
  color: var(--text-dim); font-size: 11px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.06em; transition: all var(--t);
  min-height: var(--touch-min);
}
.welcome-btn:hover { background: var(--surface3); color: var(--text); border-color: var(--text-faint); }
.welcome-btn i { font-size: 10px; }
.welcome-btn-ghost { background: transparent; border-color: var(--border); color: var(--text-faint); }
.welcome-btn-ghost:hover { background: var(--surface2); color: var(--text-dim); border-color: var(--border2); }

.welcome-meta {
  display: flex; align-items: center; gap: 6px;
  flex-wrap: wrap; justify-content: center;
}
.welcome-meta-item {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 7px 14px;
  background: transparent; border: 1px solid var(--border);
  border-radius: var(--r); color: var(--text-faint);
  font-size: 12px; font-weight: 500; font-family: var(--font-sans);
  text-decoration: none; cursor: pointer;
  transition: all var(--t); min-height: 34px;
}
.welcome-meta-item:hover { color: var(--text-dim); border-color: var(--border2); background: var(--surface2); }
.welcome-meta-item i { font-size: 12px; }
.welcome-meta-sha a { color: inherit; text-decoration: none; font-family: var(--font-mono); }
.welcome-meta-sha a:hover { color: var(--accent); }

/* Streak */
.welcome-streak {
  display: flex; align-items: center; gap: 7px;
  font-size: 13px; color: var(--text-dim);
}
.welcome-streak i { color: #f97316; font-size: 16px; }
#streak-count { font-family: var(--font-mono); font-size: 20px; font-weight: 700; color: #f97316; }
.streak-label { font-size: 11px; color: var(--text-faint); text-transform: uppercase; letter-spacing: 0.08em; }

/* Topic progress */
.topic-progress-row {
  width: min(380px, 85%); align-self: center;
  display: flex; flex-direction: column; gap: 5px;
}
.tp-item {
  display: flex; align-items: center; gap: 8px;
}
.tp-label {
  font-size: 10px; color: var(--text-faint); width: 80px;
  flex-shrink: 0; text-align: right;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.tp-bar-wrap {
  flex: 1; height: 4px; background: var(--surface3);
  border-radius: 2px; overflow: hidden;
}
.tp-bar { height: 100%; border-radius: 2px; background: var(--accent); transition: width 500ms ease; }
.tp-count { font-family: var(--font-mono); font-size: 9px; color: var(--text-faint); width: 36px; flex-shrink: 0; }

/* ── PROJECT VIEW ────────────────────────── */
.project-view {
  display: flex; flex-direction: column;
  height: 100%; overflow: hidden; animation: rise 200ms ease;
}
.pv-header {
  padding: 8px 14px; border-bottom: 1px solid var(--border);
  display: flex; align-items: center;
  justify-content: space-between; gap: 10px;
  background: var(--surface); flex-shrink: 0;
  min-height: 56px;
}
.pv-left { flex: 1; min-width: 0; }
.pv-title {
  font-family: var(--font-mono); font-size: 14px;
  font-weight: 600; color: var(--text); letter-spacing: -0.02em;
  margin-bottom: 4px; white-space: nowrap;
  overflow: hidden; text-overflow: ellipsis;
}
.pv-meta { display: flex; align-items: center; gap: 5px; flex-wrap: wrap; }
.diff-pill {
  font-family: var(--font-mono); font-size: 9px; font-weight: 600;
  padding: 2px 6px; border-radius: 2px;
  text-transform: uppercase; letter-spacing: 0.06em;
}
.pill-easy   { color: var(--easy);   background: rgba(74,222,128,0.07);  border: 1px solid rgba(74,222,128,0.2); }
.pill-medium { color: var(--medium); background: rgba(250,204,21,0.07);  border: 1px solid rgba(250,204,21,0.2); }
.pill-hard   { color: var(--hard);   background: rgba(248,113,113,0.07); border: 1px solid rgba(248,113,113,0.2); }
.pill-expert { color: var(--expert); background: rgba(192,132,252,0.07); border: 1px solid rgba(192,132,252,0.2); }
.topic-pill {
  font-size: 10px; color: var(--text-faint);
  padding: 2px 6px; border: 1px solid var(--border); border-radius: 2px;
}
.pv-num-pill {
  font-family: var(--font-mono); font-size: 10px;
  color: var(--text-faint); padding: 2px 5px;
}
.pv-author-pill {
  display: inline-flex; align-items: center; gap: 4px;
  font-size: 10px; color: var(--text-faint);
  padding: 2px 7px; border: 1px solid var(--border);
  border-radius: 2px;
}
.pv-author-pill i { font-size: 8px; }
.proj-author {
  display: inline-flex; align-items: center; gap: 3px;
  font-family: var(--font-mono); font-size: 9px;
  color: var(--text-faint); margin-left: 2px;
}
.proj-author i { font-size: 7px; }
.pv-actions { display: flex; gap: 5px; flex-shrink: 0; align-items: center; }

/* ── BUTTONS ─────────────────────────────── */
.btn {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 6px 12px; border-radius: var(--r);
  font-size: 10px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.06em;
  transition: all var(--t); border: none; white-space: nowrap;
  min-height: 32px;
}
.btn i { font-size: 10px; }
.btn-ghost {
  background: transparent; color: var(--text-faint);
  border: 1px solid var(--border);
}
.btn-ghost:hover  { color: var(--text-dim); border-color: var(--border2); background: var(--surface2); }
.btn-ghost:disabled { opacity: 0.3; cursor: not-allowed; }
.btn-solved {
  background: transparent;
  color: var(--text-faint);
  border: 1px solid var(--border);
  pointer-events: none;
}
.btn-solved.done {
  color: var(--easy);
  border-color: rgba(74,222,128,0.35);
  background: rgba(74,222,128,0.06);
}
@keyframes solvedFlash {
  0%   { background: rgba(74,222,128,0.28); border-color: var(--easy); box-shadow: 0 0 10px rgba(74,222,128,0.2); }
  100% { background: rgba(74,222,128,0.06); border-color: rgba(74,222,128,0.35); box-shadow: none; }
}
.btn-solved.done.flash { animation: solvedFlash 900ms ease-out forwards; }
.btn-run {
  background: var(--surface3); color: var(--text);
  border: 1px solid var(--border2); min-width: 72px; justify-content: center;
}
.btn-run:hover    { background: var(--surface2); border-color: var(--text-faint); }
.btn-run:disabled { opacity: 0.35; cursor: not-allowed; }
.btn-stop {
  background: rgba(248,113,113,0.08); color: var(--hard);
  border: 1px solid rgba(248,113,113,0.3); min-width: 72px; justify-content: center;
}
.btn-stop:hover { background: rgba(248,113,113,0.15); border-color: var(--hard); }
.btn-submit {
  background: rgba(74,222,128,0.08); color: var(--easy);
  border: 1px solid rgba(74,222,128,0.3); min-width: 72px; justify-content: center;
}
.btn-submit:hover { background: rgba(74,222,128,0.15); border-color: var(--easy); }
.btn-submit:disabled { opacity: 0.4; cursor: not-allowed; }
.btn-danger {
  background: rgba(248,113,113,0.1); color: var(--hard);
  border: 1px solid rgba(248,113,113,0.3);
}
.btn-danger:hover { background: rgba(248,113,113,0.2); }
.btn-reveal {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 18px; background: var(--surface2);
  border: 1px solid var(--border2); border-radius: var(--r);
  color: var(--text-dim); font-size: 10px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.06em; transition: all var(--t);
  min-height: var(--touch-min);
}
.btn-reveal:hover { background: var(--surface3); color: var(--text); border-color: var(--text-faint); }
.btn-reveal i { font-size: 10px; }

/* ── TAB BAR ─────────────────────────────── */
.tab-bar {
  display: flex; background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 10px; flex-shrink: 0;
  role: tablist;
}
.tab {
  display: flex; align-items: center; gap: 5px;
  padding: 10px 12px; font-size: 10px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.08em;
  cursor: pointer; color: var(--text-faint);
  border-bottom: 2px solid transparent;
  margin-bottom: -1px; transition: all var(--t); user-select: none;
  min-height: 40px;
}
.tab i { font-size: 11px; }
.tab:hover { color: var(--text-dim); }
.tab.active { color: var(--text); border-bottom-color: var(--accent); }

/* ── CONTENT AREA ───────────────────────── */
.content-area { flex: 1; overflow: hidden; display: flex; flex-direction: column; }
.tab-panel { display: none; flex: 1; flex-direction: column; overflow: hidden; }
.tab-panel.active { display: flex; }

/* ── PROBLEM TAB ─────────────────────────── */
.problem-scroll {
  overflow-y: auto; flex: 1; padding: 20px 24px;
}
.problem-scroll::-webkit-scrollbar { width: 2px; }
.problem-scroll::-webkit-scrollbar-thumb { background: var(--border2); }

.section-block { margin-bottom: 24px; }
.section-title {
  font-family: var(--font-mono); font-size: 9px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.12em;
  color: var(--text-faint); margin-bottom: 10px;
  padding-bottom: 6px; border-bottom: 1px solid var(--border);
  display: flex; align-items: center; gap: 6px;
}
.section-title i { font-size: 9px; }
.problem-desc { font-size: 13px; color: var(--text-dim); line-height: 1.9; }
.problem-desc code {
  font-family: var(--font-mono); font-size: 12px; color: var(--text);
  background: var(--surface2); padding: 1px 5px;
  border-radius: 2px; border: 1px solid var(--border);
}
.examples { display: flex; flex-direction: column; gap: 8px; }
.example {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r); padding: 12px 14px;
}
.example-label {
  font-family: var(--font-mono); font-size: 9px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--text-faint); margin-bottom: 8px;
  display: flex; align-items: center; gap: 5px;
}
.example-label i { font-size: 9px; }
.example-line {
  display: flex; align-items: baseline; gap: 8px;
  font-size: 12.5px; color: var(--text-dim); line-height: 1.7; margin-bottom: 3px;
  flex-wrap: wrap;
}
.example-line:last-child { margin-bottom: 0; }
.example-line strong {
  color: var(--text-dim); font-weight: 600; min-width: 48px;
  font-family: var(--font-mono); font-size: 11px;
  display: flex; align-items: center; gap: 4px; flex-shrink: 0;
}
.example-line strong i { font-size: 9px; color: var(--text-faint); }
.example-sep { color: var(--text-faint); font-size: 11px; }
.example-line code {
  font-family: var(--font-mono); font-size: 12px;
  color: var(--text); background: var(--surface2);
  padding: 1px 6px; border-radius: 2px; border: 1px solid var(--border);
}
.example-output { align-items: flex-start !important; }
.example-output-pre {
  font-family: var(--font-mono); font-size: 11.5px;
  color: var(--text); background: var(--surface2);
  border: 1px solid var(--border); border-radius: 2px;
  padding: 4px 8px; margin: 0;
  white-space: pre; line-height: 1.6; overflow-x: auto;
}
.example-explain {
  margin-top: 6px; font-size: 11.5px; color: var(--text-faint);
  line-height: 1.65; border-top: 1px solid var(--border); padding-top: 6px;
}

/* Output label warning */
.output-label-warning {
  display: flex; align-items: flex-start; gap: 9px;
  padding: 9px 12px; margin-bottom: 18px;
  background: rgba(250,204,21,0.05);
  border: 1px solid rgba(250,204,21,0.2);
  border-left: 3px solid rgba(250,204,21,0.5);
  border-radius: var(--r); font-size: 11.5px;
  color: var(--text-dim); line-height: 1.7;
}
.output-label-warning i { color: var(--medium); flex-shrink: 0; margin-top: 2px; }
.output-label-warning code {
  font-family: var(--font-mono); font-size: 11px; color: var(--medium);
  background: rgba(250,204,21,0.08); padding: 0 4px;
  border-radius: 2px; border: 1px solid rgba(250,204,21,0.2);
}

/* ── HINTS ───────────────────────────────── */
.hints-list {
  list-style: none; display: flex; flex-direction: column; gap: 6px;
  margin-bottom: 10px;
}
.hint-item {
  display: flex; align-items: flex-start; gap: 8px;
  font-size: 13px; color: var(--text-dim); line-height: 1.65;
  animation: rise 200ms ease;
}
.hint-item i { color: var(--accent); font-size: 10px; margin-top: 4px; flex-shrink: 0; }
.hint-controls { display: flex; align-items: center; gap: 8px; margin-top: 4px; }
.btn-hint {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 6px 14px; background: transparent;
  border: 1px solid var(--border); border-radius: var(--r);
  color: var(--text-faint); font-size: 10px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.06em;
  transition: all var(--t); min-height: 32px;
}
.btn-hint:hover { color: var(--accent); border-color: rgba(96,165,250,0.35); background: rgba(96,165,250,0.05); }
.btn-hint i { font-size: 10px; }
.hints-exhausted {
  font-size: 11px; color: var(--easy);
  display: flex; align-items: center; gap: 5px;
}
.hints-exhausted i { font-size: 10px; }
.no-hints { font-size: 12px; color: var(--text-faint); font-style: italic; }

/* ── EDITOR TAB ─────────────────────────── */
.editor-panel {
  display: flex; flex-direction: column;
  height: 100%; overflow: hidden;
}
.editor-bar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 5px 10px; background: var(--surface);
  border-bottom: 1px solid var(--border); flex-shrink: 0;
}
.editor-bar-left  { display: flex; align-items: center; gap: 8px; }
.editor-bar-right { display: flex; gap: 5px; align-items: center; }
.lang-tag {
  font-family: var(--font-mono); font-size: 9px; font-weight: 600;
  color: var(--text-faint); padding: 2px 6px;
  border: 1px solid var(--border); border-radius: 2px;
  letter-spacing: 0.05em; display: flex; align-items: center; gap: 4px;
}
.lang-tag i { font-size: 10px; }
.filename { font-family: var(--font-mono); font-size: 11px; color: var(--text-faint); }
.shortcut { font-size: 10px; color: var(--text-faint); opacity: 0.45; display: flex; align-items: center; gap: 4px; }
.shortcut i { font-size: 9px; }

/* ── CODEMIRROR WRAPPER ─────────────────── */
#cm-wrap {
  flex: 1;
  overflow: hidden;
  min-height: 80px;
}
#cm-wrap .CodeMirror {
  height: 100%;
  background: #0a0a0a;
  color: #c8c8c8;
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.65;
  border: none;
}

/* ── RESIZE HANDLE ───────────────────────── */
.resize-handle {
  height: 8px; flex-shrink: 0;
  background: var(--surface); border-top: 1px solid var(--border);
  cursor: ns-resize; display: flex; align-items: center; justify-content: center;
  transition: background var(--t);
  /* Larger touch target */
  touch-action: none;
}
.resize-handle:hover { background: var(--surface2); }
.resize-handle-bar {
  width: 28px; height: 2px;
  background: var(--border2); border-radius: 1px;
  transition: background var(--t);
}
.resize-handle:hover .resize-handle-bar { background: var(--text-faint); }

/* ── CODEMIRROR THEME ────────────────────── */
.cm-s-pylab .CodeMirror-gutters {
  background: #0a0a0a;
  border-right: 1px solid var(--border);
}
.cm-s-pylab .CodeMirror-linenumber { color: #3a3a3a; padding: 0 8px 0 4px; }
.cm-s-pylab .CodeMirror-cursor     { border-left: 1px solid #c8c8c8; }
.cm-s-pylab .CodeMirror-selected   { background: #252525; }
.cm-s-pylab .CodeMirror-activeline-background { background: #111111; }
.cm-s-pylab .cm-keyword   { color: #c084fc; }
.cm-s-pylab .cm-def       { color: #60a5fa; }
.cm-s-pylab .cm-variable  { color: #c8c8c8; }
.cm-s-pylab .cm-variable-2{ color: #94a3b8; }
.cm-s-pylab .cm-property  { color: #94a3b8; }
.cm-s-pylab .cm-operator  { color: #94a3b8; }
.cm-s-pylab .cm-number    { color: #fb923c; }
.cm-s-pylab .cm-string    { color: #86efac; }
.cm-s-pylab .cm-string-2  { color: #86efac; }
.cm-s-pylab .cm-comment   { color: #444444; font-style: italic; }
.cm-s-pylab .cm-builtin   { color: #34d399; }
.cm-s-pylab .cm-atom      { color: #fb923c; }
.cm-s-pylab .cm-meta      { color: #94a3b8; }
.cm-s-pylab .cm-bracket   { color: #888888; }
.cm-s-pylab .cm-tag       { color: #60a5fa; }
.cm-s-pylab .cm-error     { color: #f87171; }
.cm-s-pylab .CodeMirror-matchingbracket { color: #fff !important; background: #333; border-radius: 1px; }

/* Autocomplete hint dropdown */
.CodeMirror-hints {
  background: var(--surface2) !important;
  border: 1px solid var(--border2) !important;
  border-radius: var(--r) !important;
  box-shadow: 0 4px 20px rgba(0,0,0,0.6) !important;
  font-family: var(--font-mono) !important;
  font-size: 12px !important;
  padding: 3px !important;
  z-index: 1000 !important;
  max-height: 200px !important;
}
.CodeMirror-hint {
  color: var(--text-dim) !important;
  padding: 3px 10px !important;
  border-radius: 2px !important;
  cursor: pointer;
}
.CodeMirror-hint-active {
  background: var(--surface3) !important;
  color: var(--text) !important;
}
.CodeMirror-scroll::-webkit-scrollbar { width: 3px; height: 3px; }
.CodeMirror-scroll::-webkit-scrollbar-thumb { background: var(--border2); }

/* ── TERMINAL ─────────────────────────────── */
.terminal-pane {
  display: flex; flex-direction: column;
  flex-shrink: 0;
  height: var(--term-h);
  min-height: 80px;
  max-height: 65vh;
  border-top: 1px solid var(--border);
  background: #080808;
}
.terminal-bar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 4px 10px; border-bottom: 1px solid var(--border);
  flex-shrink: 0; background: var(--surface);
}
.terminal-label {
  font-family: var(--font-mono); font-size: 9px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.12em;
  color: var(--text-faint); display: flex; align-items: center; gap: 5px;
}
.terminal-label i { font-size: 10px; }
.terminal-bar-right { display: flex; align-items: center; gap: 10px; }
.term-clear-btn {
  background: transparent; border: none;
  color: var(--text-faint); font-size: 11px;
  padding: 4px 6px; cursor: pointer;
  transition: color var(--t); display: flex; align-items: center;
  min-width: 28px; min-height: 28px; justify-content: center;
}
.term-clear-btn:hover { color: var(--text-dim); }
.exec-time {
  font-family: var(--font-mono); font-size: 9px;
  color: var(--text-faint); padding: 0 6px;
  border-right: 1px solid var(--border);
}
.status-row {
  display: flex; align-items: center; gap: 5px;
  font-family: var(--font-mono); font-size: 9px; color: var(--text-faint);
}
.status-dot {
  width: 5px; height: 5px; border-radius: 50%;
  background: var(--border2); transition: background 200ms; flex-shrink: 0;
}
.status-dot.idle    { background: var(--border2); }
.status-dot.running { background: var(--medium); animation: blink 600ms infinite; }
.status-dot.success { background: var(--easy); }
.status-dot.error   { background: var(--hard); }
@keyframes blink { 0%,100%{opacity:1;} 50%{opacity:0.2;} }

.terminal-body {
  flex: 1; overflow-y: auto;
  padding: 10px 14px 4px;
  font-family: var(--font-mono); font-size: 12.5px; line-height: 1.65;
}
.terminal-body::-webkit-scrollbar { width: 2px; }
.terminal-body::-webkit-scrollbar-thumb { background: var(--border2); }
.term-placeholder {
  color: var(--text-faint); font-style: italic; font-size: 12px;
  display: flex; align-items: center; gap: 6px;
}
.term-placeholder i { font-size: 11px; }
.term-dim         { color: var(--text-faint); font-style: italic; }
.term-line        { color: #c8c8c8; white-space: pre-wrap; word-break: break-word; }
.term-err         { color: #f87171; }
.term-input-echo  { color: #888888; }

.terminal-input-row {
  display: flex; align-items: center;
  padding: 3px 14px 7px;
  flex-shrink: 0; border-top: 1px solid #1a1a1a;
  gap: 0; min-height: 32px;
}
.term-prompt {
  font-family: var(--font-mono); font-size: 12.5px;
  color: #555; white-space: pre; flex-shrink: 0;
}
.terminal-input-field {
  flex: 1; background: transparent; border: none; outline: none;
  font-family: var(--font-mono); font-size: 12.5px;
  color: #d8d8d8; caret-color: #d8d8d8; padding: 0;
  line-height: 1.65; min-width: 0;
  /* Prevent iOS zoom */
  font-size: max(16px, 12.5px);
}
@media (min-width: 769px) {
  .terminal-input-field { font-size: 12.5px; }
}
.terminal-input-field::placeholder { color: #2e2e2e; font-style: italic; }
.terminal-input-field:disabled { color: #3a3a3a; cursor: default; }
.terminal-input-field:disabled::placeholder { color: #2a2a2a; }

/* ── SOLUTION TAB ─────────────────────────── */
.solution-scroll { overflow-y: auto; flex: 1; padding: 20px 24px; }
.solution-scroll::-webkit-scrollbar { width: 2px; }
.solution-scroll::-webkit-scrollbar-thumb { background: var(--border2); }
.solution-lock {
  display: flex; flex-direction: column; align-items: center;
  justify-content: center; gap: 14px; padding: 52px 24px; text-align: center;
}
.lock-mark {
  width: 44px; height: 44px;
  border: 1px solid var(--border2); border-radius: var(--r2);
  display: flex; align-items: center; justify-content: center;
  color: var(--text-faint); font-size: 17px;
}
.lock-text { font-size: 12px; color: var(--text-faint); max-width: 280px; line-height: 1.75; }
.sol-lock-warning {
  display: flex; align-items: center; gap: 7px;
  font-size: 11px; color: var(--medium);
  background: rgba(250,204,21,0.06); border: 1px solid rgba(250,204,21,0.2);
  border-radius: var(--r); padding: 8px 12px; max-width: 300px;
  line-height: 1.5; text-align: left;
}
.sol-lock-warning i { font-size: 11px; flex-shrink: 0; }
.sol-code-block { display: none; }

.section-title-row {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 10px; padding-bottom: 6px; border-bottom: 1px solid var(--border);
}
.section-title-row .section-title {
  margin-bottom: 0; padding-bottom: 0; border-bottom: none;
}
.btn-copy {
  display: inline-flex; align-items: center; gap: 5px;
  padding: 4px 10px; background: transparent;
  border: 1px solid var(--border); border-radius: var(--r);
  color: var(--text-faint); font-family: var(--font-mono);
  font-size: 10px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.05em;
  cursor: pointer; transition: all var(--t); min-height: 28px;
}
.btn-copy:hover  { color: var(--text); border-color: var(--border2); background: var(--surface2); }
.btn-copy.copied { color: var(--easy); border-color: rgba(74,222,128,0.3); background: rgba(74,222,128,0.06); }
.btn-copy i { font-size: 10px; }
.solution-pre {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r); padding: 14px 16px;
  font-size: 12.5px; line-height: 1.7; overflow-x: auto;
  color: var(--text-dim); white-space: pre; margin-bottom: 20px;
}
.solution-pre::-webkit-scrollbar { height: 2px; }
.solution-pre::-webkit-scrollbar-thumb { background: var(--border2); }

/* Syntax token colors inside solution-pre — exact match to pylab editor theme */
.solution-pre .cm-keyword   { color: #c084fc; }
.solution-pre .cm-def       { color: #60a5fa; }
.solution-pre .cm-variable  { color: #c8c8c8; }
.solution-pre .cm-variable-2{ color: #94a3b8; }
.solution-pre .cm-property  { color: #94a3b8; }
.solution-pre .cm-operator  { color: #94a3b8; }
.solution-pre .cm-number    { color: #fb923c; }
.solution-pre .cm-string    { color: #86efac; }
.solution-pre .cm-string-2  { color: #86efac; }
.solution-pre .cm-comment   { color: #444444; font-style: italic; }
.solution-pre .cm-builtin   { color: #34d399; }
.solution-pre .cm-atom      { color: #fb923c; }
.solution-pre .cm-meta      { color: #94a3b8; }
.solution-pre .cm-bracket   { color: #888888; }
.solution-pre .cm-tag       { color: #60a5fa; }
.solution-pre .cm-error     { color: #f87171; }
.solution-explanation { font-size: 13px; color: var(--text-dim); line-height: 1.85; }
.solution-explanation code {
  font-family: var(--font-mono); font-size: 11.5px; color: var(--text);
  background: var(--surface2); padding: 1px 5px;
  border-radius: 2px; border: 1px solid var(--border);
}

/* ── MODAL ───────────────────────────────── */
.modal-backdrop {
  position: fixed; inset: 0; z-index: 500;
  background: rgba(0,0,0,0.7); backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  display: flex; align-items: center; justify-content: center;
  animation: fadeIn 150ms ease;
  padding: 16px;
}
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.modal {
  background: var(--surface); border: 1px solid var(--border2);
  border-radius: var(--r2); padding: 28px 28px 22px;
  max-width: 320px; width: 100%;
  display: flex; flex-direction: column; align-items: center;
  gap: 12px; text-align: center; animation: rise 150ms ease;
}
.modal-icon {
  width: 42px; height: 42px;
  background: rgba(250,204,21,0.08); border: 1px solid rgba(250,204,21,0.25);
  border-radius: var(--r2); display: flex; align-items: center; justify-content: center;
  color: var(--medium); font-size: 18px;
}
.modal-title { font-family: var(--font-mono); font-size: 14px; font-weight: 600; color: var(--text); }
.modal-body  { font-size: 12px; color: var(--text-dim); line-height: 1.7; }
.modal-actions { display: flex; gap: 8px; margin-top: 4px; flex-wrap: wrap; justify-content: center; }

/* ── AUTH MODAL ──────────────────────────── */
.auth-modal {
  width: min(440px, 96vw);
  background: var(--surface); border-radius: var(--r2);
  overflow: hidden; box-shadow: 0 24px 64px rgba(0,0,0,0.6);
  animation: rise 160ms ease;
}
.auth-step {
  padding: 32px 32px 28px;
  display: flex; flex-direction: column; gap: 20px;
}
.auth-step-header {
  display: flex; flex-direction: column; gap: 8px;
}
.auth-pitch-logo {
  width: 38px; height: 38px;
  border: 1px solid var(--border2); border-radius: var(--r2);
  display: flex; align-items: center; justify-content: center;
  color: var(--text-dim); font-size: 16px; margin-bottom: 2px;
}
.auth-pitch-name {
  font-family: var(--font-mono); font-size: 22px;
  font-weight: 700; color: var(--text); letter-spacing: -0.04em;
}
.auth-pitch-sub { font-size: 12px; color: var(--text-faint); line-height: 1.6; }
.auth-pitch-list {
  list-style: none; display: flex; flex-direction: column; gap: 11px;
}
.auth-pitch-list li {
  display: flex; align-items: flex-start; gap: 10px;
  font-size: 13px; color: var(--text-dim); line-height: 1.5;
}
.auth-pitch-list li i { color: var(--accent); font-size: 12px; margin-top: 2px; flex-shrink: 0; }
.auth-pitch-list li strong { color: var(--text); }
.auth-step-actions {
  display: flex; flex-direction: column; gap: 10px;
}
.auth-skip {
  background: transparent; border: none; color: var(--text-faint);
  font-size: 11px; cursor: pointer; padding: 0;
  display: flex; align-items: center; justify-content: center; gap: 6px;
  transition: color var(--t);
}
.auth-skip:hover { color: var(--text-dim); }
.auth-skip i { font-size: 10px; }

/* Step nav (back button + dots) */
.auth-step-nav {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: -4px;
}
.auth-back {
  background: transparent; border: none; color: var(--text-faint);
  font-size: 11px; font-weight: 600; cursor: pointer; padding: 0;
  display: flex; align-items: center; gap: 6px;
  transition: color var(--t); text-transform: uppercase; letter-spacing: 0.06em;
}
.auth-back:hover { color: var(--text-dim); }
.auth-back i { font-size: 10px; }
.auth-step-dots { display: flex; gap: 5px; align-items: center; }
.auth-dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--border2); transition: background var(--t);
}
.auth-dot.active { background: var(--accent); }

.auth-tabs { display: flex; gap: 4px; }
.auth-tab {
  flex: 1; padding: 8px; background: transparent;
  border: 1px solid var(--border); border-radius: var(--r);
  color: var(--text-faint); font-size: 12px; font-weight: 600;
  cursor: pointer; transition: all var(--t);
}
.auth-tab:hover { color: var(--text-dim); border-color: var(--border2); }
.auth-tab.active { background: var(--surface2); color: var(--text); border-color: var(--border2); }
.auth-form { display: flex; flex-direction: column; gap: 14px; }
.auth-field { display: flex; flex-direction: column; gap: 5px; }
.auth-label { font-size: 11px; font-weight: 600; color: var(--text-dim); }
.auth-input {
  background: var(--surface2); border: 1px solid var(--border);
  border-radius: var(--r); padding: 10px 12px;
  color: var(--text); font-size: 13px; font-family: var(--font-sans);
  outline: none; transition: border-color var(--t); width: 100%;
}
.auth-input:focus { border-color: var(--accent); }
.auth-hint { font-size: 10px; color: var(--text-faint); }
.auth-input-wrap {
  position: relative; display: flex; align-items: center;
}
.auth-input-wrap .auth-input { flex: 1; padding-right: 38px; }
.auth-eye {
  position: absolute; right: 0; top: 0; bottom: 0;
  width: 38px; display: flex; align-items: center; justify-content: center;
  background: transparent; border: none; color: var(--text-faint);
  cursor: pointer; transition: color var(--t); font-size: 13px;
}
.auth-eye:hover { color: var(--text-dim); }
.auth-error { font-size: 11px; color: var(--hard); min-height: 16px; }
.auth-submit {
  width: 100%; padding: 11px; background: var(--accent);
  border: none; border-radius: var(--r); color: #000;
  font-size: 13px; font-weight: 700; cursor: pointer;
  display: flex; align-items: center; justify-content: center; gap: 8px;
  transition: opacity var(--t);
}
.auth-submit:hover { opacity: 0.88; }
.auth-submit:disabled { opacity: 0.5; cursor: not-allowed; }

/* Account badge in header */
.auth-user-badge {
  display: inline-flex; align-items: center; gap: 6px;
  font-family: var(--font-mono); font-size: 10px;
  color: var(--text-faint); padding: 3px 8px;
  border: 1px solid var(--border); border-radius: var(--r);
  cursor: pointer; transition: all var(--t); background: transparent;
  position: relative;
}
.auth-user-badge:hover { color: var(--text-dim); border-color: var(--border2); }
.auth-user-badge i { font-size: 10px; }
.auth-user-menu {
  position: absolute; top: calc(100% + 6px); right: 0;
  background: var(--surface); border: 1px solid var(--border2);
  border-radius: var(--r2); min-width: 140px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.4);
  z-index: 300; overflow: hidden;
  display: none;
}
.auth-user-menu.open { display: block; }
.auth-menu-item {
  display: flex; align-items: center; gap: 8px;
  padding: 10px 14px; font-size: 12px; color: var(--text-dim);
  cursor: pointer; transition: background var(--t); border: none;
  background: transparent; text-align: left;
}
.auth-menu-item:hover { background: var(--surface2); color: var(--text); }
.auth-menu-item.danger { color: var(--hard); }
.auth-menu-item.danger:hover { background: rgba(248,113,113,0.08); }
.auth-menu-item i { font-size: 11px; width: 14px; }

/* Per-problem leaderboard panel */
.lb-panel { overflow-y: auto; flex: 1; padding: 16px; }
.lb-panel::-webkit-scrollbar { width: 2px; }
.lb-panel::-webkit-scrollbar-thumb { background: var(--border2); }
.lb-loading, .lb-empty {
  display: flex; align-items: center; justify-content: center;
  gap: 8px; padding: 32px; color: var(--text-faint); font-size: 13px;
  flex-direction: column;
}
.lb-empty i { font-size: 24px; opacity: 0.3; }
.lb-your-rank {
  background: rgba(96,165,250,0.06); border: 1px solid rgba(96,165,250,0.2);
  border-radius: var(--r); padding: 10px 14px; margin-bottom: 14px;
  display: flex; align-items: center; gap: 10px; font-size: 12px;
}
.lb-your-rank i { color: var(--accent); }
.lb-your-rank strong { color: var(--text); font-family: var(--font-mono); }
.lb-table { width: 100%; border-collapse: collapse; }
.lb-table th {
  font-size: 9px; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.1em; color: var(--text-faint);
  padding: 0 8px 8px; text-align: left; border-bottom: 1px solid var(--border);
}
.lb-table th:last-child { text-align: right; }
.lb-table td {
  padding: 9px 8px; font-size: 12px; color: var(--text-dim);
  border-bottom: 1px solid var(--border);
}
.lb-table td:last-child { text-align: right; font-family: var(--font-mono); }
.lb-table tr:last-child td { border-bottom: none; }
.lb-table tr.lb-me td { color: var(--accent); }
.lb-rank { font-family: var(--font-mono); font-size: 10px; color: var(--text-faint); }
.lb-rank-1 { color: #fbbf24; }
.lb-rank-2 { color: #94a3b8; }
.lb-rank-3 { color: #b45309; }
.lb-username { font-weight: 500; color: var(--text); }
.lb-time { color: var(--easy); }

/* Global leaderboard panel */
.glb-tabs {
  display: flex; border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}
.glb-tab {
  flex: 1; padding: 9px 0; background: transparent; border: none;
  font-size: 10px; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.07em; color: var(--text-faint); cursor: pointer;
  border-bottom: 2px solid transparent; margin-bottom: -1px;
  transition: all var(--t);
}
.glb-tab:hover { color: var(--text-dim); }
.glb-tab.active { color: var(--text); border-bottom-color: var(--accent); }
.glb-row {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 16px; border-bottom: 1px solid var(--border);
  transition: background var(--t);
}
.glb-header {
  border-bottom: 1px solid var(--border);
  margin-bottom: 4px;
  padding-bottom: 6px;
}
.glb-header span {
  font-size: 10px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-faint);
}
.glb-row:hover { background: var(--surface2); }
.glb-row:last-child { border-bottom: none; }
.glb-pos { font-family: var(--font-mono); font-size: 10px; color: var(--text-faint); width: 20px; flex-shrink: 0; }
.glb-name { font-size: 12px; font-weight: 500; color: var(--text); flex: 1; }
.glb-val { font-family: var(--font-mono); font-size: 11px; color: var(--text-faint); }
.glb-badge {
  font-size: 9px; font-weight: 600; text-transform: uppercase;
  padding: 2px 6px; border-radius: 2px; letter-spacing: 0.05em;
}

/* ── SPINNER ─────────────────────────────── */
.spin { display: inline-block; animation: spin 700ms linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ── GLOBAL SCROLLBAR ────────────────────── */
* { scrollbar-width: thin; scrollbar-color: var(--border2) transparent; }

/* ── EMPTY STATE ─────────────────────────── */
.empty-state {
  padding: 28px 16px; text-align: center;
  font-size: 11px; color: var(--text-faint);
  display: flex; flex-direction: column; align-items: center; gap: 10px;
}
.empty-state i { font-size: 20px; opacity: 0.4; }
.empty-state-reset {
  background: transparent; border: 1px solid var(--border);
  border-radius: var(--r); color: var(--text-faint);
  font-size: 9px; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.06em; padding: 4px 10px; cursor: pointer;
  transition: all var(--t); margin-top: 4px;
}
.empty-state-reset:hover { color: var(--accent); border-color: rgba(96,165,250,0.35); }

/* ═══════════════════════════════════════════
   RESPONSIVE — MOBILE FIRST
   ═══════════════════════════════════════════ */

/* ── 768px and below ─────────────────────── */
@media (max-width: 768px) {
  :root {
    --sidebar-w: min(300px, 85vw);
    --term-h: 180px;
  }

  /* Show hamburger, hide desktop sidebar */
  .hamburger { display: flex; }
  .app { grid-template-columns: 1fr; }

  /* Sidebar slides in as overlay */
  .sidebar {
    position: fixed;
    top: var(--header-h); left: 0; bottom: 0;
    width: var(--sidebar-w);
    z-index: 160;
    transform: translateX(-100%);
    box-shadow: 4px 0 24px rgba(0,0,0,0.4);
  }
  .sidebar.open { transform: translateX(0); }
  .sidebar-overlay.open { display: block; }
  .sidebar-close { display: flex; }

  /* Hide verbose labels, show icon-only on small screens */
  .shortcut    { display: none; }
  .btn-label   { display: none; }
  .tab-label   { display: none; }
  /* Keep submit label visible since it carries important state text */
  .btn-submit .btn-label { display: inline; }

  /* Project header wraps on small screens */
  .pv-header   { flex-wrap: nowrap; gap: 6px; padding: 8px 10px; min-height: auto; align-items: center; }
  .pv-left     { flex: 1; min-width: 0; }
  .pv-actions  { flex-shrink: 0; justify-content: flex-end; }
  .pv-title    { font-size: 13px; }

  /* Make tab targets larger on mobile */
  .tab { padding: 12px 14px; flex: 1; justify-content: center; }

  /* Problem scroll: tighter padding */
  .problem-scroll  { padding: 14px 16px; }
  .solution-scroll { padding: 14px 16px; }

  /* Bigger tap targets in project list */
  .proj-item { min-height: 52px; padding: 10px 8px; }
  .proj-name { font-size: 13px; }

  /* Run/Stop buttons — bigger on mobile */
  .btn-run, .btn-stop { min-width: 48px; padding: 8px 12px; }

  /* Header badges: keep only solved count and auth badge on mobile */
  .hbadge:not(#solved-count):not(.auth-user-badge):not(#auth-signin-btn) { display: none; }
  /* Auth badge — icon only on mobile */
  #auth-username-display { display: none; }
  .auth-user-badge .fa-chevron-down { display: none; }

  /* Terminal font slightly bigger for readability */
  .terminal-body { font-size: 13px; }
}

/* ── 360px and below ─────────────────────── */
@media (max-width: 360px) {
  /* Solved count — hide label, keep numbers */
  #solved-count .solved-text { display: none; }
  .header-right { gap: 4px; }
}

/* ── 480px and below ─────────────────────── */
@media (max-width: 480px) {
  :root { --term-h: 160px; }

  .stats-row  { flex-wrap: wrap; }
  .stat-cell  { min-width: 56px; padding: 8px 12px; }
  .welcome h1 { font-size: 26px; }
  .welcome p  { font-size: 12px; }
  .welcome    { gap: 14px; padding: 1.2rem; }

  /* pv-meta wraps cleanly */
  .pv-meta { gap: 4px; }
  .pv-num-pill { display: none; }

  /* Editor bar: tighten */
  .editor-bar { padding: 4px 8px; }
  .filename   { display: none; }
  .lang-tag   { padding: 2px 5px; }

  /* Hint button full-width */
  .btn-hint { width: 100%; justify-content: center; }

  /* Solution scroll tighter */
  .solution-pre { font-size: 11.5px; padding: 10px 12px; }
}

/* ── Very small screens (320px) ─────────── */
@media (max-width: 360px) {
  .pv-actions { gap: 4px; }
  .btn { padding: 5px 8px; font-size: 9px; }
  .tab { padding: 10px 8px; }
}

/* Prevent editor resize handle on mobile */
@media (max-width: 768px) {
  .resize-handle {
    height: 10px; /* bigger touch area */
  }
}

/* ── Landscape mobile — avoid squeezed layout */
@media (max-height: 500px) and (max-width: 900px) {
  :root { --term-h: 130px; }
  .pv-header { min-height: 44px; padding: 4px 10px; }
  .tab { padding: 8px 10px; }
}

/* ═══════════════════════════════════════════
   SOLVED CELEBRATION
   ═══════════════════════════════════════════ */
#solved-celebration {
  position: fixed; inset: 0; z-index: 600;
  display: flex; align-items: center; justify-content: center;
  background: rgba(0,0,0,0);
  transition: background 300ms ease;
  pointer-events: none;
  padding: 16px;
}
#solved-celebration.solv-visible {
  background: rgba(0,0,0,0.6);
  pointer-events: all;
}
#solved-celebration.solv-hiding {
  background: rgba(0,0,0,0);
  pointer-events: none;
}

#solv-canvas {
  position: absolute; inset: 0;
  pointer-events: none;
  z-index: 0;
}

.solv-card {
  position: relative; z-index: 1;
  background: var(--surface);
  border: 1px solid var(--border2);
  border-radius: 8px;
  padding: 32px 36px 24px;
  display: flex; flex-direction: column; align-items: center;
  gap: 10px; text-align: center;
  width: 100%; max-width: 340px;
  box-shadow: 0 24px 64px rgba(0,0,0,0.5);

  opacity: 0;
  transform: scale(0.85) translateY(16px);
  transition: opacity 300ms ease, transform 300ms cubic-bezier(0.34, 1.56, 0.64, 1);
}
#solved-celebration.solv-visible .solv-card {
  opacity: 1;
  transform: scale(1) translateY(0);
}
#solved-celebration.solv-hiding .solv-card {
  opacity: 0;
  transform: scale(0.92) translateY(8px);
  transition: opacity 280ms ease, transform 280ms ease;
}

.solv-icon-wrap {
  width: 56px; height: 56px;
  border-radius: 50%;
  background: rgba(74,222,128,0.1);
  border: 1px solid rgba(74,222,128,0.3);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 4px;
}
.solv-check {
  font-size: 24px; color: var(--easy);
  animation: solv-pop 400ms cubic-bezier(0.34, 1.56, 0.64, 1) 120ms both;
}
@keyframes solv-pop {
  from { transform: scale(0); opacity: 0; }
  to   { transform: scale(1); opacity: 1; }
}

.solv-title {
  font-family: var(--font-mono);
  font-size: 26px; font-weight: 600;
  color: var(--easy); letter-spacing: -0.02em;
  line-height: 1;
}
.solv-problem {
  font-family: var(--font-mono);
  font-size: 13px; color: var(--text);
  font-weight: 500; letter-spacing: -0.01em;
}
.solv-meta {
  display: flex; align-items: center; gap: 6px;
  margin-top: 2px; flex-wrap: wrap; justify-content: center;
}
.solv-diff {
  font-family: var(--font-mono); font-size: 9px; font-weight: 600;
  padding: 2px 7px; border-radius: 2px;
  text-transform: uppercase; letter-spacing: 0.06em;
}
.solv-topic {
  font-size: 10px; color: var(--text-faint);
  padding: 2px 7px; border: 1px solid var(--border); border-radius: 2px;
}

.solv-actions {
  display: flex; gap: 8px; margin-top: 12px; flex-wrap: wrap; justify-content: center;
  width: 100%;
}
.solv-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 9px 18px; border-radius: var(--r);
  font-size: 10px; font-weight: 600;
  text-transform: uppercase; letter-spacing: 0.06em;
  transition: all var(--t); border: 1px solid var(--border2);
  cursor: pointer; font-family: inherit;
  min-height: var(--touch-min); flex: 1; justify-content: center;
}
.solv-btn i { font-size: 10px; }
.solv-btn-next {
  background: rgba(74,222,128,0.1); color: var(--easy);
  border-color: rgba(74,222,128,0.35);
}
.solv-btn-next:hover {
  background: rgba(74,222,128,0.18); border-color: var(--easy);
}
.solv-btn-close {
  background: transparent; color: var(--text-faint);
}
.solv-btn-close:hover {
  background: var(--surface2); color: var(--text-dim);
}

@media (max-width: 400px) {
  .solv-card { padding: 24px 20px 18px; }
  .solv-title { font-size: 22px; }
  .solv-btn { padding: 10px 12px; font-size: 9px; }
}