/* ═══════════════════════════════════════════
   QuizCraft – Premium Dark UI
   ═══════════════════════════════════════════ */

/* ── Reset & Tokens ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --bg: #0b0e17;
  --surface: rgba(255,255,255,.05);
  --surface-hover: rgba(255,255,255,.09);
  --glass-border: rgba(255,255,255,.08);
  --text: #e8ecf4;
  --text-dim: #8a94a6;
  --accent: #6c63ff;
  --accent-glow: rgba(108,99,255,.35);
  --green: #34d399;
  --green-glow: rgba(52,211,153,.25);
  --red: #f87171;
  --red-glow: rgba(248,113,113,.25);
  --danger: #ef4444;
  --radius: 16px;
  --radius-sm: 10px;
  --transition: .25s cubic-bezier(.4,0,.2,1);
}

html { font-size: 16px; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  overflow-x: hidden;
  /* Animated gradient blobs */
  background-image:
    radial-gradient(ellipse 600px 600px at 15% 10%, rgba(108,99,255,.12), transparent),
    radial-gradient(ellipse 500px 500px at 85% 80%, rgba(52,211,153,.08), transparent);
}

/* ── Typography ── */
h1 { font-size: 1.75rem; font-weight: 800; letter-spacing: -.02em; }
h2 { font-size: 1.25rem; font-weight: 700; }
.subtitle { color: var(--text-dim); margin-top: .35rem; font-size: .95rem; }

/* ── Navigation ── */
#main-nav {
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  background: rgba(11,14,23,.72);
  border-bottom: 1px solid var(--glass-border);
}
.nav-inner {
  max-width: 640px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  padding: .75rem 1.25rem;
}
.logo { font-weight: 800; font-size: 1.2rem; letter-spacing: -.01em; }
.logo span { color: var(--accent); }

.nav-tabs { display: flex; gap: .5rem; }
.nav-btn {
  display: flex; align-items: center; gap: .4rem;
  padding: .5rem 1rem;
  border: none; border-radius: 999px;
  background: var(--surface);
  color: var(--text-dim);
  font-family: var(--font); font-size: .85rem; font-weight: 600;
  cursor: pointer;
  transition: background var(--transition), color var(--transition), box-shadow var(--transition);
}
.nav-btn:hover { background: var(--surface-hover); color: var(--text); }
.nav-btn.active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 0 20px var(--accent-glow);
}

/* ── Main ── */
#app {
  max-width: 640px; margin: 0 auto;
  padding: 1.5rem 1.25rem 4rem;
}
.section-header { margin-bottom: 1.5rem; }

.tab-panel { display: none; animation: fadeUp .35s ease; }
.tab-panel.active { display: block; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Glass Card ── */
.glass-card {
  background: var(--surface);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: border-color var(--transition);
}
.glass-card:hover { border-color: rgba(255,255,255,.14); }

/* ── Form ── */
.form-group { display: flex; flex-direction: column; gap: .4rem; margin-bottom: 1rem; }
.form-group label {
  font-size: .8rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: .06em; color: var(--text-dim);
}

textarea, input[type="text"] {
  width: 100%;
  padding: .7rem .9rem;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  background: rgba(255,255,255,.04);
  color: var(--text);
  font-family: var(--font); font-size: .95rem;
  resize: vertical;
  transition: border-color var(--transition), box-shadow var(--transition);
}
textarea:focus, input[type="text"]:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.choices-row { display: grid; grid-template-columns: 1fr 1fr; gap: .75rem; }

/* answer toggle */
.answer-toggle { display: flex; gap: .5rem; }
.toggle-btn {
  flex: 1;
  padding: .6rem;
  border: 2px solid var(--glass-border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-dim);
  font-family: var(--font); font-size: 1rem; font-weight: 700;
  cursor: pointer;
  transition: all var(--transition);
}
.toggle-btn:hover { border-color: var(--accent); color: var(--text); }
.toggle-btn.selected {
  border-color: var(--accent);
  background: var(--accent);
  color: #fff;
  box-shadow: 0 0 16px var(--accent-glow);
}

/* ── Buttons ── */
.btn-primary {
  display: inline-flex; align-items: center; gap: .45rem;
  width: 100%; justify-content: center;
  padding: .75rem 1.5rem;
  border: none; border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), #8b5cf6);
  color: #fff;
  font-family: var(--font); font-size: .95rem; font-weight: 700;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px var(--accent-glow);
}
.btn-primary:active { transform: translateY(0); }

.btn-secondary {
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .6rem 1.2rem;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--text);
  font-family: var(--font); font-size: .88rem; font-weight: 600;
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition);
}
.btn-secondary:hover { background: var(--surface-hover); border-color: rgba(255,255,255,.18); }

.btn-danger {
  display: inline-flex; align-items: center; gap: .35rem;
  padding: .45rem .9rem;
  border: 1px solid rgba(239,68,68,.25);
  border-radius: var(--radius-sm);
  background: rgba(239,68,68,.1);
  color: var(--danger);
  font-family: var(--font); font-size: .8rem; font-weight: 600;
  cursor: pointer;
  transition: background var(--transition);
}
.btn-danger:hover { background: rgba(239,68,68,.2); }

/* ── Saved List ── */
#saved-list-section { margin-top: 2rem; }
.list-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 1rem;
}
.badge {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 1.5rem; padding: .1rem .45rem;
  border-radius: 999px;
  background: var(--accent);
  color: #fff; font-size: .75rem; font-weight: 700;
  margin-left: .4rem;
}

.question-list { list-style: none; display: flex; flex-direction: column; gap: .6rem; }
.question-item {
  display: flex; align-items: flex-start; justify-content: space-between; gap: .75rem;
  padding: .85rem 1rem;
  background: var(--surface);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  animation: fadeUp .3s ease;
}
.question-item .q-body { flex: 1; min-width: 0; }
.question-item .q-num {
  font-size: .7rem; font-weight: 700; color: var(--accent);
  text-transform: uppercase; letter-spacing: .06em;
}
.question-item .q-text {
  font-size: .92rem; margin-top: .15rem;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.question-item .q-meta {
  font-size: .78rem; color: var(--text-dim); margin-top: .25rem;
}
.question-item .q-delete {
  flex-shrink: 0;
  background: none; border: none; color: var(--text-dim);
  cursor: pointer; padding: .3rem;
  transition: color var(--transition);
}
.question-item .q-delete:hover { color: var(--danger); }

.empty-state {
  text-align: center;
  color: var(--text-dim);
  padding: 2rem 1rem;
  font-size: .95rem;
}

/* ── Solve Tab ── */
.empty-solve {
  text-align: center; padding: 3rem 1.5rem;
}
.empty-icon { font-size: 3rem; margin-bottom: 1rem; }
.empty-solve p { color: var(--text-dim); line-height: 1.7; }
.empty-solve strong { color: var(--accent); }

/* progress */
.progress-bar-wrap {
  width: 100%; height: 6px;
  background: var(--surface);
  border-radius: 99px; overflow: hidden;
  margin-bottom: .35rem;
}
.progress-bar {
  height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--accent), #8b5cf6);
  border-radius: 99px;
  transition: width .4s ease;
}
.progress-text {
  text-align: center; font-size: .82rem; font-weight: 600;
  color: var(--text-dim); margin-bottom: 1rem;
}

/* quiz card */
.quiz-card { text-align: center; }
.quiz-question {
  font-size: 1.15rem; font-weight: 700;
  line-height: 1.6;
  margin-bottom: 1.5rem;
  white-space: pre-wrap;
}

.quiz-choices { display: flex; flex-direction: column; gap: .6rem; }
.choice-btn {
  display: flex; align-items: center; gap: .75rem;
  width: 100%; padding: .85rem 1rem;
  border: 2px solid var(--glass-border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text);
  font-family: var(--font); font-size: .95rem; font-weight: 500;
  cursor: pointer;
  text-align: left;
  transition: all var(--transition);
}
.choice-btn:hover { border-color: var(--accent); background: rgba(108,99,255,.08); }
.choice-label {
  display: flex; align-items: center; justify-content: center;
  width: 2rem; height: 2rem;
  border-radius: 50%;
  background: var(--surface-hover);
  font-weight: 700; font-size: .85rem;
  flex-shrink: 0;
}

/* states */
.choice-btn.correct {
  border-color: var(--green);
  background: var(--green-glow);
}
.choice-btn.correct .choice-label { background: var(--green); color: #fff; }
.choice-btn.wrong {
  border-color: var(--red);
  background: var(--red-glow);
}
.choice-btn.wrong .choice-label { background: var(--red); color: #fff; }
.choice-btn.disabled { pointer-events: none; opacity: .65; }

/* feedback */
.feedback {
  margin-top: 1rem;
  padding: .6rem 1rem;
  border-radius: var(--radius-sm);
  font-size: .9rem; font-weight: 600;
  text-align: center;
}
.feedback.correct-fb { background: var(--green-glow); color: var(--green); }
.feedback.wrong-fb   { background: var(--red-glow);   color: var(--red); }

/* quiz nav */
.quiz-nav {
  display: flex; justify-content: space-between;
  margin-top: 1.25rem;
}

/* result */
.result-card { text-align: center; margin-top: 1.5rem; }
.result-score { font-size: 2.5rem; font-weight: 800; margin: .75rem 0 .25rem; color: var(--accent); }
.result-label { color: var(--text-dim); margin-bottom: 1.25rem; font-weight: 600; }

/* ── Toast ── */
.toast {
  position: fixed; bottom: 2rem; left: 50%; transform: translateX(-50%) translateY(100px);
  padding: .65rem 1.25rem;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: #fff; font-size: .88rem; font-weight: 600;
  box-shadow: 0 8px 32px var(--accent-glow);
  opacity: 0;
  transition: transform .4s ease, opacity .4s ease;
  white-space: nowrap;
  z-index: 200;
}
.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ── Utility ── */
.hidden { display: none !important; }

/* ── Mobile ── */
@media (max-width: 600px) {
  h1 { font-size: 1.4rem; }
  .glass-card { padding: 1.15rem; }
  .choices-row { grid-template-columns: 1fr; }
  .nav-btn span { display: none; }
  .nav-btn { padding: .5rem .75rem; }
}