:root {
  --bg: #0d1117;
  --bg2: #161b22;
  --card: #1c2330;
  --border: #2d3646;
  --text: #e6edf3;
  --muted: #8b949e;
  --green: #2ea043;
  --green-bright: #3fb950;
  --blue: #388bfd;
  --red: #f85149;
  --radius: 12px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; width: 100%; }

/* ---------- topbar ---------- */
.topbar {
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
}
.topbar-inner {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 60px;
}
.brand {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
}
.nav { display: flex; gap: 4px; flex: 1; }
.nav a {
  color: var(--muted);
  text-decoration: none;
  padding: 8px 14px;
  border-radius: 8px;
  font-size: 0.95rem;
}
.nav a:hover, .nav a.active { color: var(--text); background: var(--card); }
.auth-area { display: flex; align-items: center; gap: 10px; }
.user-chip { font-size: 0.9rem; color: var(--muted); }

/* ---------- buttons ---------- */
.btn {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  padding: 9px 18px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.95rem;
  text-decoration: none;
  display: inline-block;
}
.btn:hover { border-color: var(--muted); }
.btn.primary { background: var(--green); border-color: var(--green); color: #fff; font-weight: 600; }
.btn.primary:hover { background: var(--green-bright); }
.btn.danger { background: transparent; border-color: var(--red); color: var(--red); }
.btn.small { padding: 6px 12px; font-size: 0.85rem; }
.btn.full { width: 100%; margin-top: 10px; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* ---------- hero ---------- */
.hero { text-align: center; padding: 56px 0 36px; }
.hero h1 { font-size: 2.4rem; margin-bottom: 12px; }
.hero h1 span { color: var(--green-bright); }
.hero p { color: var(--muted); font-size: 1.1rem; max-width: 600px; margin: 0 auto 24px; }
.searchbar {
  display: flex; gap: 8px; max-width: 520px; margin: 0 auto;
}
.searchbar input {
  flex: 1; padding: 12px 16px; border-radius: 10px;
  border: 1px solid var(--border); background: var(--bg2); color: var(--text);
  font-size: 1rem;
}

/* ---------- cards & grids ---------- */
.section-title { font-size: 1.3rem; margin: 32px 0 16px; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  cursor: pointer;
  transition: transform 0.12s, border-color 0.12s;
}
.card:hover { transform: translateY(-2px); border-color: var(--green); }
.card h3 { font-size: 1.15rem; margin-bottom: 6px; }
.card p { color: var(--muted); font-size: 0.9rem; }
.card .code {
  display: inline-block; font-size: 0.75rem; font-weight: 700;
  background: var(--bg2); border: 1px solid var(--border);
  padding: 3px 10px; border-radius: 20px; margin-bottom: 10px; color: var(--green-bright);
}

/* ---------- breadcrumbs ---------- */
.crumbs { margin: 24px 0 8px; color: var(--muted); font-size: 0.9rem; }
.crumbs a { color: var(--blue); text-decoration: none; }
.crumbs a:hover { text-decoration: underline; }

/* ---------- semester pills ---------- */
.sem-pills { display: flex; flex-wrap: wrap; gap: 10px; margin: 16px 0 24px; }
.sem-pill {
  padding: 10px 20px; border-radius: 24px; border: 1px solid var(--border);
  background: var(--card); color: var(--text); cursor: pointer; font-size: 0.95rem;
}
.sem-pill.active { background: var(--green); border-color: var(--green); color: #fff; font-weight: 600; }

/* ---------- material rows ---------- */
.mat-group { margin-bottom: 28px; }
.mat-group h3 { font-size: 1.05rem; margin-bottom: 12px; color: var(--green-bright); }
.mat-row {
  display: flex; align-items: center; gap: 14px;
  background: var(--card); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 18px; margin-bottom: 10px;
}
.mat-row .icon { font-size: 1.5rem; }
.mat-row .info { flex: 1; min-width: 0; }
.mat-row .info .title { font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.mat-row .info .meta { color: var(--muted); font-size: 0.85rem; margin-top: 3px; }
.badge {
  font-size: 0.72rem; font-weight: 700; padding: 3px 10px; border-radius: 20px;
  background: var(--bg2); border: 1px solid var(--border); color: var(--muted);
  white-space: nowrap;
}
.badge.pending { color: #d29922; border-color: #d29922; }

/* ---------- forms ---------- */
.form-card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 28px; max-width: 640px; margin: 24px auto;
}
.form-card h2 { margin-bottom: 6px; }
.form-card .sub { color: var(--muted); margin-bottom: 20px; font-size: 0.95rem; }
.form-card label { display: block; margin-bottom: 14px; font-size: 0.9rem; color: var(--muted); }
.form-card input, .form-card select {
  width: 100%; margin-top: 6px; padding: 11px 14px; border-radius: 8px;
  border: 1px solid var(--border); background: var(--bg2); color: var(--text); font-size: 1rem;
}
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.form-error { color: var(--red); margin-top: 12px; font-size: 0.9rem; min-height: 1.2em; }
.form-ok { color: var(--green-bright); margin-top: 12px; font-size: 0.9rem; }
.hint { color: var(--muted); font-size: 0.85rem; margin-top: 10px; }

/* ---------- leaderboard ---------- */
.lb-row {
  display: flex; align-items: center; gap: 16px;
  background: var(--card); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 20px; margin-bottom: 10px;
}
.lb-rank { font-size: 1.4rem; font-weight: 800; width: 44px; color: var(--green-bright); }
.lb-row .name { flex: 1; font-weight: 600; }
.lb-row .count { color: var(--muted); font-size: 0.9rem; }

/* ---------- modal ---------- */
.modal-backdrop {
  position: fixed; inset: 0; background: rgba(0,0,0,0.6);
  display: flex; align-items: center; justify-content: center; z-index: 100;
  padding: 20px;
}
.modal {
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: 14px; padding: 28px; width: 100%; max-width: 400px; position: relative;
}
.modal-close {
  position: absolute; top: 12px; right: 14px; background: none; border: none;
  color: var(--muted); font-size: 1.1rem; cursor: pointer;
}
.tabs { display: flex; gap: 8px; margin-bottom: 20px; }
.tab {
  flex: 1; padding: 10px; border-radius: 8px; border: 1px solid var(--border);
  background: var(--card); color: var(--muted); cursor: pointer; font-size: 1rem;
}
.tab.active { background: var(--green); color: #fff; border-color: var(--green); font-weight: 600; }
.modal label { display: block; margin-bottom: 12px; font-size: 0.9rem; color: var(--muted); }
.modal input {
  width: 100%; margin-top: 6px; padding: 11px 14px; border-radius: 8px;
  border: 1px solid var(--border); background: var(--bg); color: var(--text); font-size: 1rem;
}

/* ---------- misc ---------- */
.loading, .empty { text-align: center; color: var(--muted); padding: 60px 0; }
.footer { margin-top: auto; border-top: 1px solid var(--border); padding: 24px 0; color: var(--muted); font-size: 0.9rem; text-align: center; }
main { flex: 1; padding-bottom: 40px; }
.admin-actions { display: flex; gap: 8px; }

@media (max-width: 640px) {
  .hero h1 { font-size: 1.8rem; }
  .form-row { grid-template-columns: 1fr; }
  .nav a { padding: 8px 8px; font-size: 0.85rem; }
  .mat-row { flex-wrap: wrap; }
}