/* ==========================================================================
   COMPETITIVE PROGRAMMING PORTAL — DESIGN SYSTEM
   Aesthetic: online-judge / terminal. Verdict colors (AC green, WA red,
   pending amber) are reserved for status & difficulty — never decoration.
   Monospace is used structurally (nav, stats, unit numbers) not just code.
   ========================================================================== */

/* ---- Font imports ---- */
@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500;600;700&display=swap');

/* ---- Design tokens ---- */
:root {
  /* Dark theme (default) */
  --bg: #0B0F14;
  --bg-raised: #121821;
  --bg-overlay: #161D27;
  --panel: #121821;
  --panel-border: #1E2733;
  --panel-border-soft: #182231;
  --text: #E6EDF3;
  --text-dim: #8B98A5;
  --text-faint: #5B6776;

  /* Signature verdict palette */
  --ac: #3FB950;        /* Accepted / Easy / Success */
  --ac-dim: #2E8B3F;
  --ac-bg: rgba(63, 185, 80, 0.12);
  --pending: #D29922;    /* Pending / Medium / Warning */
  --pending-bg: rgba(210, 153, 34, 0.12);
  --wa: #F85149;         /* Wrong Answer / Hard / Danger */
  --wa-bg: rgba(248, 81, 73, 0.12);
  --info: #58A6FF;       /* Links / informational accent */
  --info-bg: rgba(88, 166, 255, 0.12);

  /* Type */
  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Layout */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --sidebar-w: 240px;
  --topbar-h: 60px;
  --max-w: 1280px;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.4);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.35);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.45);

  --transition: 180ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg: #F6F8FA;
  --bg-raised: #FFFFFF;
  --bg-overlay: #FFFFFF;
  --panel: #FFFFFF;
  --panel-border: #D8DEE4;
  --panel-border-soft: #E5E9ED;
  --text: #1B2330;
  --text-dim: #57606A;
  --text-faint: #8B98A5;

  --ac: #1A7F37;
  --ac-dim: #166A2E;
  --ac-bg: rgba(26, 127, 55, 0.10);
  --pending: #9A6700;
  --pending-bg: rgba(154, 103, 0, 0.10);
  --wa: #CF222E;
  --wa-bg: rgba(207, 34, 46, 0.10);
  --info: #0969DA;
  --info-bg: rgba(9, 105, 218, 0.10);

  --shadow-sm: 0 1px 2px rgba(27,35,48,0.06);
  --shadow-md: 0 4px 16px rgba(27,35,48,0.08);
  --shadow-lg: 0 12px 32px rgba(27,35,48,0.12);
}

/* ---- Reset ---- */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background var(--transition), color var(--transition);
  min-height: 100vh;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; }
input, select, textarea { font-family: inherit; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

:focus-visible {
  outline: 2px solid var(--info);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---- Typography ---- */
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.2;
  color: var(--text);
}
h1 { font-size: clamp(2rem, 4vw, 2.75rem); font-weight: 700; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); }
h3 { font-size: 1.25rem; }
h4 { font-size: 1.05rem; }
p { color: var(--text-dim); }
.mono { font-family: var(--font-mono); }
.text-dim { color: var(--text-dim); }
.text-faint { color: var(--text-faint); }

/* ---- Layout shell ---- */
.app-shell {
  display: flex;
  min-height: 100vh;
}

/* Top bar — styled like a terminal title bar */
.topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--topbar-h);
  background: var(--bg-raised);
  border-bottom: 1px solid var(--panel-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px 0 20px;
  z-index: 200;
}
.topbar-left { display: flex; align-items: center; gap: 14px; }
.topbar-dots { display: flex; gap: 6px; }
.topbar-dots span {
  width: 10px; height: 10px; border-radius: 50%;
  display: inline-block;
}
.topbar-dots span:nth-child(1) { background: var(--wa); }
.topbar-dots span:nth-child(2) { background: var(--pending); }
.topbar-dots span:nth-child(3) { background: var(--ac); }

.brand {
  display: flex;
  align-items: center;
  gap: 9px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text);
}
.brand .prompt-symbol {
  color: var(--ac);
  font-family: var(--font-mono);
}
.brand .course-code {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--text-faint);
  border: 1px solid var(--panel-border);
  border-radius: 4px;
  padding: 2px 6px;
}

.topbar-right { display: flex; align-items: center; gap: 10px; }

.icon-btn {
  width: 36px; height: 36px;
  display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  transition: background var(--transition), color var(--transition);
}
.icon-btn:hover { background: var(--bg-overlay); color: var(--text); }

.hamburger { display: none; }

/* Search bar in topbar */
.topbar-search {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-sm);
  padding: 7px 12px;
  width: 280px;
  color: var(--text-faint);
  transition: border-color var(--transition);
}
.topbar-search:focus-within { border-color: var(--info); }
.topbar-search input {
  background: none;
  border: none;
  color: var(--text);
  font-size: 0.85rem;
  width: 100%;
  outline: none;
}
.topbar-search .kbd-hint {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  border: 1px solid var(--panel-border);
  border-radius: 4px;
  padding: 1px 5px;
  color: var(--text-faint);
  white-space: nowrap;
}

/* Sidebar (desktop) */
.sidebar {
  position: fixed;
  top: var(--topbar-h);
  left: 0;
  bottom: 0;
  width: var(--sidebar-w);
  background: var(--bg-raised);
  border-right: 1px solid var(--panel-border);
  overflow-y: auto;
  padding: 18px 12px 24px;
  z-index: 150;
}
.sidebar-section-label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-faint);
  padding: 8px 10px 6px;
}
.sidebar nav a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 10px;
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-size: 0.88rem;
  font-weight: 500;
  margin-bottom: 2px;
  transition: background var(--transition), color var(--transition);
  position: relative;
}
.sidebar nav a i { width: 16px; text-align: center; font-size: 0.85rem; }
.sidebar nav a:hover { background: var(--bg-overlay); color: var(--text); }
.sidebar nav a.active {
  background: var(--ac-bg);
  color: var(--ac);
}
.sidebar nav a.active::before {
  content: '';
  position: absolute;
  left: -12px;
  top: 0; bottom: 0;
  width: 3px;
  background: var(--ac);
  border-radius: 0 3px 3px 0;
}

.sidebar-progress {
  margin-top: 18px;
  padding: 14px 12px;
  background: var(--bg-overlay);
  border: 1px solid var(--panel-border-soft);
  border-radius: var(--radius-md);
}
.sidebar-progress-label {
  font-size: 0.72rem;
  color: var(--text-faint);
  font-family: var(--font-mono);
  margin-bottom: 8px;
  display: flex;
  justify-content: space-between;
}
.progress-track {
  height: 6px;
  border-radius: 3px;
  background: var(--panel-border);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--ac-dim), var(--ac));
  border-radius: 3px;
  transition: width 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Main content */
.main-content {
  margin-left: var(--sidebar-w);
  margin-top: var(--topbar-h);
  flex: 1;
  width: calc(100% - var(--sidebar-w));
  min-height: calc(100vh - var(--topbar-h));
}

.page-container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 32px 28px 64px;
}

.page-header {
  margin-bottom: 28px;
}
.page-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ac);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.page-eyebrow::before { content: '$'; color: var(--text-faint); }
.page-header p.lede {
  margin-top: 8px;
  max-width: 640px;
  font-size: 0.98rem;
}

/* ---- Buttons ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  font-family: var(--font-body);
  transition: all var(--transition);
  border: 1px solid transparent;
  white-space: nowrap;
}
.btn-primary {
  background: var(--ac);
  color: #07140A;
}
.btn-primary:hover { background: var(--ac-dim); transform: translateY(-1px); }
.btn-secondary {
  background: var(--bg-overlay);
  color: var(--text);
  border-color: var(--panel-border);
}
.btn-secondary:hover { border-color: var(--text-faint); }
.btn-ghost {
  color: var(--text-dim);
  padding: 9px 12px;
}
.btn-ghost:hover { color: var(--text); }
.btn-sm { padding: 6px 11px; font-size: 0.78rem; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* ---- Cards / panels ---- */
.card {
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-md);
  transition: border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}
.card-hover:hover {
  border-color: var(--text-faint);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Glass variant for hero/feature surfaces */
.glass {
  background: rgba(18, 24, 33, 0.6);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border: 1px solid rgba(255,255,255,0.08);
}
[data-theme="light"] .glass {
  background: rgba(255,255,255,0.7);
  border: 1px solid rgba(27,35,48,0.06);
}

/* ---- Badges / tags ---- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  padding: 3px 8px;
  border-radius: 5px;
  letter-spacing: 0.02em;
}
.badge-ac { background: var(--ac-bg); color: var(--ac); }
.badge-pending { background: var(--pending-bg); color: var(--pending); }
.badge-wa { background: var(--wa-bg); color: var(--wa); }
.badge-info { background: var(--info-bg); color: var(--info); }
.badge-neutral { background: var(--bg-overlay); color: var(--text-dim); border: 1px solid var(--panel-border); }

.tag {
  display: inline-block;
  font-size: 0.72rem;
  padding: 3px 9px;
  border-radius: 20px;
  background: var(--bg-overlay);
  color: var(--text-dim);
  border: 1px solid var(--panel-border-soft);
}

/* Difficulty pills - use verdict colors purposefully */
.diff-easy { color: var(--ac); }
.diff-medium { color: var(--pending); }
.diff-hard { color: var(--wa); }

/* ---- Hero ---- */
.hero {
  position: relative;
  border-radius: var(--radius-lg);
  padding: 56px 40px;
  overflow: hidden;
  background: var(--bg-raised);
  border: 1px solid var(--panel-border);
  margin-bottom: 32px;
}
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--panel-border-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--panel-border-soft) 1px, transparent 1px);
  background-size: 32px 32px;
  opacity: 0.4;
  mask-image: radial-gradient(ellipse 80% 60% at 30% 20%, black, transparent);
}
.hero-content { position: relative; z-index: 1; max-width: 680px; }
.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ac);
  background: var(--ac-bg);
  padding: 5px 12px;
  border-radius: 20px;
  margin-bottom: 18px;
}
.hero-tag .dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--ac);
  animation: pulse-dot 2s infinite;
}
@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}
.hero h1 { margin-bottom: 14px; }
.hero p.hero-desc { font-size: 1.02rem; max-width: 560px; margin-bottom: 26px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.hero-stats {
  display: flex;
  gap: 28px;
  margin-top: 36px;
  flex-wrap: wrap;
}
.hero-stat .num {
  font-family: var(--font-mono);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text);
}
.hero-stat .label {
  font-size: 0.74rem;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ---- Grid utilities ---- */
.grid {
  display: grid;
  gap: 18px;
}
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-auto { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }

.section { margin-bottom: 48px; }
.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 18px;
  gap: 12px;
  flex-wrap: wrap;
}
.section-head h2 { display: flex; align-items: center; gap: 10px; }
.section-head .unit-no {
  font-family: var(--font-mono);
  color: var(--text-faint);
  font-size: 0.9rem;
}

/* ---- Quick nav cards (homepage) ---- */
.nav-card {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.nav-card .icon-wrap {
  width: 38px; height: 38px;
  border-radius: 9px;
  display: flex; align-items: center; justify-content: center;
  background: var(--ac-bg);
  color: var(--ac);
  font-size: 1rem;
}
.nav-card h4 { margin-top: 4px; }
.nav-card p { font-size: 0.84rem; }
.nav-card .arrow { margin-top: auto; color: var(--text-faint); font-size: 0.8rem; display: flex; align-items: center; gap: 6px; transition: gap var(--transition), color var(--transition); }
.nav-card:hover .arrow { gap: 10px; color: var(--ac); }

/* ---- Announcement list ---- */
.announcement {
  display: flex;
  gap: 14px;
  padding: 16px;
  border-bottom: 1px solid var(--panel-border-soft);
}
.announcement:last-child { border-bottom: none; }
.announcement .a-icon {
  width: 34px; height: 34px;
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  font-size: 0.85rem;
}
.announcement .a-body { flex: 1; min-width: 0; }
.announcement .a-title { font-weight: 600; font-size: 0.9rem; margin-bottom: 2px; }
.announcement .a-msg { font-size: 0.84rem; color: var(--text-dim); }
.announcement .a-date { font-family: var(--font-mono); font-size: 0.7rem; color: var(--text-faint); white-space: nowrap; }
.announcement.pinned { background: var(--bg-overlay); border-radius: var(--radius-sm); margin-bottom: 4px; }

/* ---- Accordion (Syllabus) ---- */
.accordion-item {
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  overflow: hidden;
  background: var(--panel);
}
.accordion-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 20px;
  cursor: pointer;
  user-select: none;
}
.accordion-header-left { display: flex; align-items: center; gap: 16px; }
.unit-badge {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--ac);
  background: var(--ac-bg);
  width: 42px; height: 42px;
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.accordion-header h3 { margin-bottom: 3px; }
.accordion-header .unit-summary { font-size: 0.82rem; color: var(--text-dim); max-width: 480px; }
.accordion-chevron {
  color: var(--text-faint);
  transition: transform var(--transition);
  flex-shrink: 0;
}
.accordion-item.open .accordion-chevron { transform: rotate(180deg); }
.accordion-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 350ms cubic-bezier(0.4, 0, 0.2, 1);
}
.accordion-item.open .accordion-body { max-height: 3000px; }
.accordion-body-inner { padding: 0 20px 20px; }

.topic-group { margin-top: 14px; }
.topic-group-heading {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-faint);
  margin-bottom: 8px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--panel-border-soft);
}
.topic-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 11px 12px;
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}
.topic-row:hover { background: var(--bg-overlay); }
.topic-check {
  width: 18px; height: 18px;
  border: 1.5px solid var(--panel-border);
  border-radius: 5px;
  flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  transition: all var(--transition);
}
.topic-check.checked {
  background: var(--ac);
  border-color: var(--ac);
  color: #07140A;
}
.topic-name { flex: 1; font-size: 0.88rem; font-weight: 500; }
.topic-complexity {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--text-faint);
  background: var(--bg-overlay);
  padding: 2px 8px;
  border-radius: 5px;
}
.topic-resources { display: flex; gap: 4px; }
.topic-resources button {
  width: 28px; height: 28px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 6px;
  color: var(--text-faint);
  font-size: 0.78rem;
  transition: all var(--transition);
}
.topic-resources button:hover { background: var(--bg-overlay); color: var(--info); }
.topic-resources button.bookmark-active { color: var(--pending); }

/* ---- Tabs ---- */
.tabs {
  display: flex;
  gap: 4px;
  border-bottom: 1px solid var(--panel-border);
  margin-bottom: 24px;
  overflow-x: auto;
}
.tab-btn {
  padding: 10px 18px;
  font-size: 0.86rem;
  font-weight: 600;
  color: var(--text-dim);
  border-bottom: 2px solid transparent;
  white-space: nowrap;
  transition: color var(--transition), border-color var(--transition);
}
.tab-btn:hover { color: var(--text); }
.tab-btn.active { color: var(--ac); border-color: var(--ac); }
.tab-panel { display: none; }
.tab-panel.active { display: block; animation: fade-in 280ms ease; }
@keyframes fade-in { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: translateY(0); } }

/* ---- Material / problem cards ---- */
.material-card {
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.material-card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; }
.material-icon {
  width: 36px; height: 36px;
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  background: var(--info-bg);
  color: var(--info);
  flex-shrink: 0;
}
.material-card h4 { font-size: 0.96rem; }
.material-card p { font-size: 0.82rem; }
.material-meta { font-size: 0.74rem; color: var(--text-faint); font-family: var(--font-mono); }
.material-tags { display: flex; gap: 6px; flex-wrap: wrap; margin: 4px 0; }
.material-actions { display: flex; gap: 8px; margin-top: 6px; }

/* ---- Problem card (practice/lab) ---- */
.problem-card {
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.problem-card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 8px; }
.problem-card h4 { font-size: 0.96rem; line-height: 1.3; }
.problem-meta-row {
  display: flex;
  gap: 14px;
  font-size: 0.78rem;
  color: var(--text-faint);
  flex-wrap: wrap;
}
.problem-meta-row span { display: flex; align-items: center; gap: 5px; }
.problem-actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 4px; }

/* ---- Lab experiment detail ---- */
.lab-card {
  padding: 22px;
  margin-bottom: 16px;
}
.lab-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 14px;
  cursor: pointer;
}
.lab-card-header h4 { display: flex; align-items: center; gap: 10px; }
.lab-no {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-faint);
}
.lab-detail { display: none; padding-top: 14px; border-top: 1px solid var(--panel-border-soft); }
.lab-card.open .lab-detail { display: block; animation: fade-in 280ms ease; }
.io-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 14px 0;
}
.io-block {
  background: var(--bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
}
.io-block .io-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 6px;
  letter-spacing: 0.05em;
}
.io-block pre {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--text);
  white-space: pre-wrap;
  word-break: break-word;
}
.lab-card .constraints {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-dim);
  background: var(--bg-overlay);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  margin-bottom: 14px;
}

/* ---- Assignment cards ---- */
.assignment-card {
  padding: 20px;
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 12px;
}
.assignment-date-block {
  text-align: center;
  background: var(--bg-overlay);
  border: 1px solid var(--panel-border-soft);
  border-radius: var(--radius-sm);
  padding: 10px 14px;
  flex-shrink: 0;
  min-width: 64px;
}
.assignment-date-block .day { font-family: var(--font-mono); font-size: 1.3rem; font-weight: 700; line-height: 1; }
.assignment-date-block .mon { font-size: 0.68rem; color: var(--text-faint); text-transform: uppercase; margin-top: 2px; }
.assignment-body { flex: 1; min-width: 0; }
.assignment-body-top { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; margin-bottom: 6px; }
.assignment-actions { display: flex; gap: 8px; margin-top: 12px; flex-wrap: wrap; align-items: center; }

/* Submission status control */
.status-select {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--panel-border);
  background: var(--bg-overlay);
  color: var(--text);
}

/* ---- Weekly planner timeline ---- */
.timeline {
  position: relative;
  padding-left: 28px;
}
.timeline::before {
  content: '';
  position: absolute;
  left: 9px; top: 6px; bottom: 6px;
  width: 2px;
  background: var(--panel-border);
}
.timeline-item {
  position: relative;
  padding-bottom: 22px;
}
.timeline-item:last-child { padding-bottom: 0; }
.timeline-dot {
  position: absolute;
  left: -28px; top: 4px;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--bg-raised);
  border: 2px solid var(--panel-border);
  display: flex; align-items: center; justify-content: center;
}
.timeline-item.has-quiz .timeline-dot { border-color: var(--pending); }
.timeline-item.has-assignment .timeline-dot { border-color: var(--info); }
.timeline-card {
  padding: 16px 18px;
}
.timeline-week-label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 6px;
}
.timeline-topics { display: flex; gap: 6px; flex-wrap: wrap; margin: 8px 0; }
.timeline-meta-row { display: flex; gap: 16px; flex-wrap: wrap; font-size: 0.8rem; margin-top: 8px; }
.timeline-meta-row span { display: flex; align-items: center; gap: 6px; color: var(--text-dim); }

/* ---- Resources page ---- */
.resource-card {
  padding: 22px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}
.resource-card .platform-icon {
  width: 48px; height: 48px;
  border-radius: 12px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem;
  background: var(--bg-overlay);
  color: var(--text);
  margin-bottom: 4px;
}
.lang-card { padding: 22px; }
.lang-card-head { display: flex; align-items: center; gap: 12px; margin-bottom: 10px; }
.lang-card-head .lang-icon { font-size: 1.4rem; color: var(--ac); }

/* ---- Faculty page ---- */
.faculty-hero {
  display: flex;
  gap: 28px;
  align-items: center;
  padding: 32px;
  flex-wrap: wrap;
}
.faculty-avatar {
  width: 120px; height: 120px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--ac-dim), var(--info));
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-display);
  font-size: 2.2rem;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}
.faculty-info h2 { margin-bottom: 4px; }
.faculty-info .role { color: var(--ac); font-family: var(--font-mono); font-size: 0.85rem; margin-bottom: 10px; }
.faculty-contact { display: flex; gap: 16px; margin-top: 14px; flex-wrap: wrap; }
.faculty-contact a { display: flex; align-items: center; gap: 7px; font-size: 0.85rem; color: var(--text-dim); transition: color var(--transition); }
.faculty-contact a:hover { color: var(--info); }

/* ---- Coding quote ---- */
.quote-block {
  padding: 24px;
  display: flex;
  gap: 16px;
  align-items: flex-start;
}
.quote-block .quote-mark { font-family: var(--font-display); font-size: 2.2rem; color: var(--ac); line-height: 1; }
.quote-block blockquote { font-family: var(--font-display); font-size: 1.05rem; font-style: normal; color: var(--text); margin-bottom: 6px; }
.quote-block cite { font-size: 0.8rem; color: var(--text-faint); font-style: normal; }

/* ---- Progress circle ---- */
.progress-circle-wrap { position: relative; width: 110px; height: 110px; }
.progress-circle-wrap svg { transform: rotate(-90deg); }
.progress-circle-bg { fill: none; stroke: var(--panel-border); stroke-width: 9; }
.progress-circle-fill { fill: none; stroke: var(--ac); stroke-width: 9; stroke-linecap: round; transition: stroke-dashoffset 700ms cubic-bezier(0.4,0,0.2,1); }
.progress-circle-label {
  position: absolute; inset: 0;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
}
.progress-circle-label .pct { font-family: var(--font-mono); font-weight: 700; font-size: 1.3rem; }
.progress-circle-label .sub { font-size: 0.65rem; color: var(--text-faint); }

/* ---- Toast notifications ---- */
.toast-container {
  position: fixed;
  bottom: 22px;
  right: 22px;
  z-index: 500;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.toast {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--bg-raised);
  border: 1px solid var(--panel-border);
  border-left: 3px solid var(--ac);
  border-radius: var(--radius-sm);
  padding: 12px 16px;
  font-size: 0.85rem;
  box-shadow: var(--shadow-lg);
  min-width: 240px;
  animation: toast-in 280ms cubic-bezier(0.4,0,0.2,1);
}
.toast.toast-warn { border-left-color: var(--pending); }
.toast.toast-error { border-left-color: var(--wa); }
@keyframes toast-in {
  from { opacity: 0; transform: translateX(20px); }
  to { opacity: 1; transform: translateX(0); }
}
.toast.leaving { animation: toast-out 220ms ease forwards; }
@keyframes toast-out { to { opacity: 0; transform: translateX(20px); } }

/* ---- Search results overlay ---- */
.search-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 400;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding-top: 12vh;
}
.search-overlay.show { display: flex; }
.search-modal {
  background: var(--bg-raised);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-lg);
  width: 90%;
  max-width: 580px;
  max-height: 60vh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
}
.search-modal-input {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 16px 18px;
  border-bottom: 1px solid var(--panel-border);
}
.search-modal-input input {
  flex: 1;
  background: none;
  border: none;
  color: var(--text);
  font-size: 1rem;
  outline: none;
}
.search-result-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 18px;
  transition: background var(--transition);
}
.search-result-item:hover { background: var(--bg-overlay); }
.search-result-item .src { font-family: var(--font-mono); font-size: 0.68rem; color: var(--text-faint); }
.search-empty { padding: 32px 18px; text-align: center; color: var(--text-faint); font-size: 0.88rem; }

/* ---- Footer ---- */
.site-footer {
  border-top: 1px solid var(--panel-border);
  padding: 28px 28px;
  margin-top: 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 0.8rem;
  color: var(--text-faint);
}
.site-footer .footer-links { display: flex; gap: 16px; }
.site-footer a:hover { color: var(--text); }

/* ---- Mobile sidebar overlay ---- */
.sidebar-overlay {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 140;
  display: none;
}
.sidebar-overlay.show { display: block; }

/* ---- Scroll reveal ---- */
.reveal { opacity: 0; transform: translateY(16px); transition: opacity 500ms ease, transform 500ms ease; }
.reveal.in-view { opacity: 1; transform: translateY(0); }

/* ---- Empty state ---- */
.empty-state {
  text-align: center;
  padding: 48px 20px;
  color: var(--text-faint);
}
.empty-state i { font-size: 1.8rem; margin-bottom: 10px; display: block; }

/* ==========================================================================
   RESPONSIVE
   ========================================================================== */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .topbar-search { width: 200px; }
}

@media (max-width: 860px) {
  .sidebar {
    transform: translateX(-100%);
    transition: transform var(--transition);
    width: 260px;
  }
  .sidebar.show { transform: translateX(0); box-shadow: var(--shadow-lg); }
  .main-content { margin-left: 0; width: 100%; }
  .hamburger { display: flex; }
  .topbar-search { display: none; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .io-grid { grid-template-columns: 1fr; }
  .hero { padding: 36px 22px; }
  .faculty-hero { flex-direction: column; text-align: center; align-items: center; }
  .faculty-contact { justify-content: center; }
  .page-container { padding: 24px 16px 48px; }
}

@media (max-width: 480px) {
  .hero-stats { gap: 18px; }
  .assignment-card { flex-direction: column; }
  .assignment-date-block { flex-direction: row; gap: 6px; min-width: unset; align-self: flex-start; }
}