:root {
  --bg: #0b0d13;
  --bg-grad: radial-gradient(circle at 15% 0%, rgba(255,138,101,.10), transparent 40%),
             radial-gradient(circle at 85% 15%, rgba(128,203,196,.10), transparent 45%),
             #0b0d13;
  --card: #151822;
  --card-2: #1c202c;
  --card-hover: #1a1e29;
  --text: #f2f4f9;
  --muted: #8b93a8;
  --muted-2: #626b80;
  --border: #262b3a;
  --coral: #ff8a65;
  --violet: #b39ddb;
  --mint: #80cbc4;
  --good: #4ade95;
  --bad: #ff6b6b;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 8px 30px rgba(0,0,0,.35);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--bg-grad);
  background-attachment: fixed;
  color: var(--text);
  min-height: 100vh;
}

.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 28px;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: rgba(11,13,19,0.85);
  backdrop-filter: blur(10px);
  z-index: 10;
}
.topbar h1 { font-size: 18px; margin: 0; font-weight: 700; letter-spacing: -.01em; }
.back {
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  padding: 7px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  transition: all .15s;
}
.back:hover { color: var(--text); border-color: var(--muted-2); }

main { max-width: 980px; margin: 0 auto; padding: 32px 20px 100px; animation: fadeIn .25s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.hero { margin-bottom: 26px; }
.hero h1 { font-size: 28px; margin: 0 0 6px; letter-spacing: -.02em; }
.hero p { color: var(--muted); margin: 0; font-size: 15px; }

.track-switcher { display: flex; gap: 8px; margin: 24px 0 26px; border-bottom: 1px solid var(--border); }
.track-button {
  background: transparent; border: 0; border-bottom: 2px solid transparent; color: var(--muted);
  padding: 11px 4px; margin-right: 18px; font-size: 14px; font-weight: 700; cursor: pointer;
}
.track-button.active { color: var(--text); border-bottom-color: var(--coral); }
.track-content { animation: fadeIn .2s ease; }
.track-note { color: var(--muted); font-size: 13px; line-height: 1.55; margin: 0 0 16px; }
.generation-actions { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 28px; }
.generation-actions button:disabled { opacity: .5; cursor: wait; }

/* ---- subject cards ---- */
.subject-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(270px, 1fr)); gap: 18px; }
.subject-card {
  background: linear-gradient(160deg, var(--card), var(--card-2));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  cursor: pointer;
  transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease;
  position: relative;
  overflow: hidden;
}
.subject-card::before {
  content: "";
  position: absolute; inset: 0;
  background: linear-gradient(160deg, var(--accent) 0%, transparent 60%);
  opacity: .06;
  pointer-events: none;
}
.subject-card:hover { transform: translateY(-4px); border-color: var(--accent); box-shadow: var(--shadow); }
.subject-card .code { color: var(--accent); font-size: 12px; letter-spacing: .08em; font-weight: 700; text-transform: uppercase; }
.subject-card h2 { margin: 8px 0 14px; font-size: 21px; letter-spacing: -.01em; }
.subject-card .stat { color: var(--muted); font-size: 13px; display: flex; align-items: center; gap: 6px; margin-top: 4px; }
.subject-card .stat .dot { width: 5px; height: 5px; border-radius: 50%; background: var(--accent); flex-shrink: 0; }
.subject-card.coral { --accent: var(--coral); }
.subject-card.violet { --accent: var(--violet); }
.subject-card.mint { --accent: var(--mint); }
.subject-card .bar { height: 3px; border-radius: 4px; background: var(--accent); margin-bottom: 16px; width: 40px; }

/* ---- lists ---- */
.section-title {
  font-size: 12px; text-transform: uppercase; letter-spacing: .1em; color: var(--muted-2);
  margin: 34px 0 12px; font-weight: 700; display: flex; align-items: center; gap: 8px;
}
.section-title::after { content: ""; flex: 1; height: 1px; background: var(--border); }
.list { display: grid; gap: 8px; }
.list-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 15px 18px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  transition: all .15s;
}
.list-item:hover { border-color: var(--accent, #555); background: var(--card-hover); transform: translateX(2px); }
.list-item .title { font-weight: 600; font-size: 15px; }
.list-item .meta { color: var(--muted); font-size: 12.5px; margin-top: 4px; line-height: 1.5; }
.pill {
  font-size: 11.5px; font-weight: 700; letter-spacing: .03em;
  background: var(--card-2); border: 1px solid var(--border); border-radius: 999px;
  padding: 6px 14px; color: var(--muted); flex-shrink: 0; text-transform: uppercase;
  transition: all .15s;
}
.list-item:hover .pill { color: var(--text); border-color: var(--accent, var(--muted-2)); }

/* ---- quiz header / progress bar ---- */
.quiz-header { margin-bottom: 20px; }
.quiz-header h2 { font-size: 19px; margin: 0 0 12px; letter-spacing: -.01em; }
.quiz-meta-row { display: flex; justify-content: space-between; align-items: center; font-size: 13px; color: var(--muted); margin-bottom: 8px; }
.quiz-meta-row .score-tag { font-weight: 700; color: var(--mint); }
.progress-track { height: 6px; border-radius: 999px; background: var(--card-2); overflow: hidden; }
.progress-fill { height: 100%; border-radius: 999px; background: linear-gradient(90deg, var(--coral), var(--mint)); transition: width .3s ease; }

/* ---- question card ---- */
.q-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
  animation: fadeIn .2s ease;
}
.q-badge {
  display: inline-block; font-size: 11px; font-weight: 700; letter-spacing: .06em;
  color: var(--muted-2); text-transform: uppercase; margin-bottom: 10px;
}
.q-text { font-size: 18px; margin-bottom: 22px; line-height: 1.55; font-weight: 500; }
.options { display: grid; gap: 10px; }
.option {
  display: flex; align-items: center; gap: 14px;
  text-align: left;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--card-2);
  color: var(--text);
  cursor: pointer;
  font-size: 14.5px;
  line-height: 1.4;
  transition: all .12s;
}
.option:hover:not(:disabled) { border-color: var(--muted-2); background: #22273400; background: #232838; }
.option .letter {
  flex-shrink: 0; width: 26px; height: 26px; border-radius: 8px;
  background: var(--bg); border: 1px solid var(--border);
  display: flex; align-items: center; justify-content: center;
  font-size: 12px; font-weight: 700; color: var(--muted);
  transition: all .12s;
}
.option .opt-text { flex: 1; }
.option.correct { border-color: var(--good); background: rgba(74,222,149,.1); }
.option.correct .letter { background: var(--good); border-color: var(--good); color: #08130d; }
.option.wrong { border-color: var(--bad); background: rgba(255,107,107,.1); }
.option.wrong .letter { background: var(--bad); border-color: var(--bad); color: #1c0808; }
.option:disabled { cursor: default; opacity: .92; }

.feedback {
  margin-top: 18px; padding: 16px 18px; border-radius: var(--radius-sm);
  font-size: 14px; line-height: 1.6; animation: fadeIn .2s ease;
}
.feedback.correct { background: rgba(74,222,149,.08); border: 1px solid rgba(74,222,149,.3); }
.feedback.wrong { background: rgba(255,107,107,.08); border: 1px solid rgba(255,107,107,.3); }
.feedback strong {
  display: flex; align-items: center; gap: 8px; margin-bottom: 6px; font-size: 14.5px;
}
.feedback.correct strong { color: var(--good); }
.feedback.wrong strong { color: var(--bad); }
.feedback .body { color: var(--text); opacity: .92; }

.nav-row { display: flex; justify-content: flex-end; margin-top: 22px; }
button.primary {
  background: linear-gradient(135deg, var(--coral), #ff7043);
  color: #1a0f0a;
  border: none;
  border-radius: 10px;
  padding: 12px 24px;
  font-weight: 700;
  font-size: 14px;
  cursor: pointer;
  transition: transform .12s, box-shadow .12s;
  box-shadow: 0 4px 14px rgba(255,138,101,.25);
}
button.primary:hover:not(:disabled) { transform: translateY(-1px); box-shadow: 0 6px 18px rgba(255,138,101,.35); }
button.primary:disabled { opacity: .35; cursor: not-allowed; box-shadow: none; }
button.ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted);
  border-radius: 10px;
  padding: 10px 18px;
  font-size: 13.5px;
  cursor: pointer;
  transition: all .15s;
}
button.ghost:hover { color: var(--text); border-color: var(--muted-2); }

/* ---- score screen ---- */
.score-box { text-align: center; padding: 50px 24px; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }
.score-box .ring {
  width: 140px; height: 140px; margin: 0 auto 22px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center; flex-direction: column;
  background: conic-gradient(var(--ring-color, var(--mint)) calc(var(--pct,0) * 1%), var(--card-2) 0);
  position: relative;
}
.score-box .ring::before { content: ""; position: absolute; inset: 8px; border-radius: 50%; background: var(--card); }
.score-box .ring .big { position: relative; font-size: 30px; font-weight: 800; }
.score-box .ring .pct { position: relative; font-size: 12px; color: var(--muted); margin-top: 2px; }
.score-box .sub { color: var(--muted); font-size: 15px; margin: 4px 0 26px; }
.score-box .sub b { color: var(--text); }
.score-actions { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }

.note { color: var(--muted); font-size: 13px; margin: -4px 0 20px; }
.empty { color: var(--muted); padding: 50px 20px; text-align: center; font-size: 14px; }
.back-row { margin-bottom: 18px; }

@media (max-width: 560px) {
  main { padding: 22px 14px 90px; }
  .q-card { padding: 20px; }
  .q-text { font-size: 16.5px; }
  .subject-grid { grid-template-columns: 1fr; }
  .track-switcher { overflow-x: auto; }
  .track-button { white-space: nowrap; }
}