:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --surface-hover: #222531;
  --border: #2a2d3a;
  --text: #e4e4e7;
  --text-muted: #9ca3af;
  --accent: #818cf8;
  --accent-soft: rgba(129, 140, 248, 0.12);
  --green: #34d399;
  --green-soft: rgba(52, 211, 153, 0.12);
  --amber: #fbbf24;
  --amber-soft: rgba(251, 191, 36, 0.12);
  --rose: #fb7185;
  --rose-soft: rgba(251, 113, 133, 0.12);
  --cyan: #22d3ee;
  --cyan-soft: rgba(34, 211, 238, 0.12);
  --sidebar-width: 230px;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

/* ── Sidebar ── */

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-width);
  height: 100vh;
  background: var(--surface);
  border-right: 1px solid var(--border);
  padding: 2rem 1.25rem;
  overflow-y: auto;
  z-index: 100;
  transition: transform 0.25s ease;
}

.sidebar-brand {
  text-decoration: none;
  display: block;
  margin-bottom: 2rem;
}

.sidebar-brand h2 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
}

.sidebar-brand p {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}

.sidebar-section {
  margin-bottom: 1.5rem;
}

.sidebar-section-title {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.65rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.6rem;
  padding-left: 0.5rem;
}

.sidebar-link {
  display: block;
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.85rem;
  padding: 0.45rem 0.65rem;
  border-radius: 8px;
  transition: all 0.15s ease;
  margin-bottom: 0.15rem;
}

.sidebar-link:hover {
  color: var(--text);
  background: var(--surface-hover);
}

.sidebar-link.active {
  color: var(--accent);
  background: var(--accent-soft);
  font-weight: 500;
}

/* ── Mobile menu toggle ── */

.menu-toggle {
  display: none;
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 200;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  width: 2.5rem;
  height: 2.5rem;
  cursor: pointer;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  line-height: 1;
}

.menu-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 50;
}

/* ── Main content ── */

.main-content {
  margin-left: var(--sidebar-width);
}

.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

header {
  text-align: center;
  margin-bottom: 3rem;
}

header h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.25rem;
}

.date-badge {
  display: inline-block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.3rem 0.75rem;
  border-radius: 999px;
  margin-top: 0.75rem;
}

/* ── Assignment cards ── */

.assignment-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin-bottom: 1rem;
  transition: background 0.15s ease;
}

.assignment-card:hover {
  background: var(--surface-hover);
}

.card-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.card-number {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  font-weight: 500;
  width: 1.75rem;
  height: 1.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  flex-shrink: 0;
}

.card-number.purple { color: var(--accent); background: var(--accent-soft); }
.card-number.green  { color: var(--green);  background: var(--green-soft); }
.card-number.amber  { color: var(--amber);  background: var(--amber-soft); }
.card-number.rose   { color: var(--rose);   background: var(--rose-soft); }
.card-number.cyan   { color: var(--cyan);   background: var(--cyan-soft); }

.card-title {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.card-body {
  padding-left: 2.5rem;
  color: var(--text-muted);
  font-size: 0.925rem;
}

.card-body p {
  margin-bottom: 0.4rem;
}

.card-body .options {
  margin-top: 0.5rem;
}

.card-body .option {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  padding: 0.15rem 0;
}

.option-bullet {
  color: var(--border);
  flex-shrink: 0;
}

/* ── Vocabulary grid ── */

.vocab-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(145px, 1fr));
  gap: 0.5rem;
  margin-top: 0.75rem;
}

.vocab-word {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.4rem 0.65rem;
  text-align: center;
}

.vocab-word.chosen {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-soft);
}

/* ── Status badge ── */

.status-badge {
  display: inline-block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.65rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  margin-left: auto;
}

.status-badge.in-progress {
  color: var(--amber);
  background: var(--amber-soft);
}

/* ── Note callout ── */

.note {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 0.75rem;
  padding: 0.75rem;
  background: var(--accent-soft);
  border-radius: 8px;
  border-left: 3px solid var(--accent);
}

/* ── Collapsible reading sections ── */

details.reading-section {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-top: 0.75rem;
  margin-bottom: 0.75rem;
}

details.reading-section summary {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--accent);
  padding: 0.65rem 0.85rem;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  user-select: none;
}

details.reading-section summary::-webkit-details-marker {
  display: none;
}

details.reading-section summary::before {
  content: '▸';
  font-size: 0.75rem;
  transition: transform 0.15s ease;
}

details.reading-section[open] summary::before {
  transform: rotate(90deg);
}

details.reading-section .reading-body {
  padding: 0 0.85rem 0.85rem;
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.75;
  max-height: 500px;
  overflow-y: auto;
  border-top: 1px solid var(--border);
}

details.reading-section .reading-body p {
  margin-bottom: 0.85rem;
}

details.reading-section .reading-body p:first-child {
  margin-top: 0.85rem;
}

details.reading-section .reading-body blockquote {
  border-left: 3px solid var(--accent);
  padding-left: 0.85rem;
  margin: 0.85rem 0;
  font-style: italic;
}

details.reading-section .reading-body h4 {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  margin: 1.25rem 0 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* ── Prompt list ── */

.prompt-list {
  list-style: none;
  padding: 0;
  margin-top: 0.75rem;
}

.prompt-list li {
  padding: 0.65rem 0.75rem;
  margin-bottom: 0.4rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.875rem;
  line-height: 1.55;
}

.prompt-list .prompt-number {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 500;
  color: var(--accent);
  margin-right: 0.35rem;
}

.prompt-list .prompt-title {
  font-weight: 600;
  color: var(--text);
}

.prompt-list .prompt-hint {
  display: block;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 0.25rem;
}

/* ── Footer ── */

footer {
  text-align: center;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* ── Mobile responsive ── */

@media (max-width: 768px) {
  .menu-toggle {
    display: flex;
  }

  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .menu-overlay.open {
    display: block;
  }

  .main-content {
    margin-left: 0;
  }

  .container {
    padding-top: 4.5rem;
  }
}