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

:root {
  --primary: #4f46e5;
  --primary-light: #6366f1;
  --success: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  -webkit-tap-highlight-color: transparent;
}

/* ===== Tab Bar ===== */
#tab-bar {
  display: flex;
  max-width: 720px;
  margin: 0 auto;
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 0 16px;
  position: sticky;
  top: 0;
  z-index: 10;
}
.tab {
  flex: 1;
  padding: 14px 10px;
  border: none;
  border-bottom: 3px solid transparent;
  background: none;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}
.tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

#app { max-width: 720px; margin: 0 auto; padding: 16px; }

/* ===== Typography ===== */
h1 { font-size: 1.5rem; text-align: center; color: var(--primary); margin-bottom: 4px; }
h2 { font-size: 1.25rem; text-align: center; margin-bottom: 12px; }
.subtitle { text-align: center; color: var(--text-secondary); font-size: 0.9rem; margin-bottom: 20px; }

/* ===== Panel ===== */
.panel { background: var(--card); border-radius: var(--radius); padding: 24px; box-shadow: var(--shadow); }

/* ===== Form ===== */
.form-group { margin-bottom: 14px; }
.form-group label { display: block; font-size: 0.82rem; font-weight: 600; color: var(--text-secondary); margin-bottom: 5px; }
.form-group input[type="number"] {
  width: 100%; padding: 10px 12px; border: 1.5px solid var(--border);
  border-radius: 8px; font-size: 1rem; background: var(--bg); color: var(--text);
}
.form-group input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79,70,229,0.1); }
.form-row { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 10px; }

/* ===== Buttons ===== */
.btn-group { display: flex; flex-wrap: wrap; gap: 6px; }
.btn-group .btn { flex: 1 1 auto; min-width: 0; font-size: 0.8rem; padding: 8px 6px; }
.btn {
  display: inline-block; padding: 9px 15px; border: 1.5px solid var(--border);
  border-radius: 8px; background: var(--card); color: var(--text);
  font-size: 0.88rem; cursor: pointer; text-align: center; transition: all 0.15s; user-select: none;
}
.btn:hover { background: var(--bg); }
.btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn-sm { padding: 6px 13px; font-size: 0.8rem; }
.btn-primary {
  display: block; width: 100%; padding: 14px; border: none; border-radius: 10px;
  background: var(--primary); color: #fff; font-size: 1.05rem; font-weight: 600;
  cursor: pointer; margin-top: 18px;
}
.btn-primary:hover { background: var(--primary-light); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }

/* ===== Quiz Header ===== */
.quiz-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 16px; padding-bottom: 12px; border-bottom: 1px solid var(--border);
}
.progress-text { font-size: 0.9rem; font-weight: 600; color: var(--text-secondary); }
.type-badge { padding: 3px 10px; border-radius: 20px; font-size: 0.75rem; font-weight: 600; background: rgba(79,70,229,0.1); color: var(--primary); }

/* ===== Question Card ===== */
.question-card { min-height: 200px; padding: 4px 0 12px; }
.q-stem {
  font-size: 1.02rem; font-weight: 600; margin-bottom: 16px; line-height: 1.7;
  padding: 12px 16px; background: var(--bg); border-radius: 10px; border-left: 4px solid var(--primary);
}

/* Options */
.q-options { display: flex; flex-direction: column; gap: 8px; }
.option-btn {
  display: block; width: 100%; padding: 12px 16px; border: 2px solid var(--border);
  border-radius: 10px; background: var(--card); font-size: 0.93rem;
  text-align: left; cursor: pointer; transition: all 0.15s; line-height: 1.4;
}
.option-btn:hover { border-color: var(--primary-light); background: rgba(99,102,241,0.05); }
.option-btn.selected { border-color: var(--primary); background: rgba(79,70,229,0.08); }
.option-btn.correct { border-color: var(--success); background: rgba(16,185,129,0.12); }
.option-btn.wrong { border-color: var(--danger); background: rgba(239,68,68,0.1); }

/* Judge */
.q-judge { display: flex; gap: 12px; }
.btn-judge {
  flex: 1; padding: 18px 16px; border: 2px solid var(--border);
  border-radius: 10px; font-size: 1.05rem; font-weight: 700;
  cursor: pointer; background: var(--card); transition: all 0.15s;
}
.btn-judge:hover { border-color: var(--primary-light); }
.btn-judge.selected { border-color: var(--primary); background: rgba(79,70,229,0.08); }
.btn-judge.correct { border-color: var(--success); background: rgba(16,185,129,0.15); }
.btn-judge.wrong { border-color: var(--danger); background: rgba(239,68,68,0.12); }

/* Fill */
.q-fill textarea {
  width: 100%; min-height: 100px; padding: 12px; border: 2px solid var(--border);
  border-radius: 10px; font-size: 0.93rem; resize: vertical; font-family: inherit; background: var(--bg);
}
.q-fill textarea:focus { outline: none; border-color: var(--primary); }

/* Feedback */
.q-feedback {
  margin-top: 14px; padding: 12px 14px; border-radius: 8px; font-size: 0.88rem; line-height: 1.6;
}
.q-feedback.correct { background: rgba(16,185,129,0.1); color: #065f46; border: 1px solid rgba(16,185,129,0.3); }
.q-feedback.wrong   { background: rgba(239,68,68,0.08); color: #991b1b; border: 1px solid rgba(239,68,68,0.2); }
.q-feedback.info    { background: rgba(79,70,229,0.06); color: #3730a3; border: 1px solid rgba(79,70,229,0.15); }

/* ===== Quiz Nav ===== */
.quiz-nav { display: flex; gap: 10px; margin-top: 18px; }
.quiz-nav .btn { flex: 1; padding: 12px 8px; font-size: 0.9rem; font-weight: 600; }
.btn-check { border-color: var(--warning); color: var(--warning); }
.btn-check:hover { background: rgba(245,158,11,0.08); }

/* ===== Result ===== */
.score-circle {
  width: 120px; height: 120px; border-radius: 50%;
  background: conic-gradient(var(--success) var(--score, 0%), var(--border) 0);
  display: flex; align-items: center; justify-content: center;
  margin: 16px auto; font-size: 2rem; font-weight: 800; color: var(--primary);
}
.score-circle::before { content: ''; position: absolute; width: 90px; height: 90px; border-radius: 50%; background: #fff; }
.score-circle { position: relative; }
.score-circle span { position: relative; z-index: 1; }
.score-detail { text-align: center; color: var(--text-secondary); margin-bottom: 8px; }

.result-summary {
  display: flex; justify-content: center; gap: 20px; margin: 12px 0 16px; font-size: 0.9rem;
}
.result-summary .stat { text-align: center; }
.result-summary .stat-num { font-size: 1.5rem; font-weight: 700; }
.result-summary .stat-num.green { color: var(--success); }
.result-summary .stat-num.red   { color: var(--danger); }
.result-summary .stat-num.gray  { color: var(--text-secondary); }
.result-summary .stat-label { font-size: 0.75rem; color: var(--text-secondary); }

.result-list { margin-bottom: 16px; }
.result-item {
  padding: 8px 0; border-bottom: 1px solid var(--border); font-size: 0.84rem;
  display: flex; gap: 8px; align-items: flex-start;
}
.result-item:last-child { border-bottom: none; }
.result-icon { flex-shrink: 0; }

/* ===== Notes ===== */
#notes-content { font-size: 0.9rem; line-height: 1.8; }
#notes-content h3 { font-size: 1.05rem; color: var(--primary); margin: 16px 0 6px; border-bottom: 2px solid var(--border); padding-bottom: 4px; }
#notes-content p { margin-bottom: 6px; }

/* ===== Responsive ===== */
@media (max-width: 480px) {
  #app { padding: 8px; }
  .panel { padding: 16px; }
  h1 { font-size: 1.2rem; }
  .form-row { grid-template-columns: 1fr 1fr; }
  .btn-group .btn { font-size: 0.75rem; padding: 7px 3px; }
  .q-stem { font-size: 0.92rem; }
  .option-btn { font-size: 0.85rem; padding: 10px 12px; }
  .btn-judge { padding: 16px 10px; font-size: 0.98rem; }
  .quiz-nav { flex-wrap: wrap; }
  .quiz-nav .btn { font-size: 0.82rem; padding: 10px 6px; }
  .result-summary { gap: 12px; }
}

@media (min-width: 768px) {
  #app { padding: 24px 16px; }
  .panel { padding: 32px; }
  h1 { font-size: 1.75rem; }
  .btn-group .btn { font-size: 0.85rem; }
}

/* Fill blanks */
.blank {
  display:inline-block;
  min-width:60px;
  padding:2px 8px;
  border-bottom:2px dashed var(--danger);
  color:var(--danger);
  font-weight:700;
  margin:0 2px;
}
.fb-detail { font-size:0.85rem; }
.fb-detail.wrong { color:#991b1b; }

/* Result item flex fix */
.result-item span { flex:1; }

/* Important badge */
.important-badge {
  display:inline-block;
  margin-left:6px;
  padding:2px 8px;
  border-radius:12px;
  font-size:0.7rem;
  font-weight:700;
  background:linear-gradient(135deg,#f59e0b,#fbbf24);
  color:#fff;
  vertical-align:middle;
  animation:pulse 2s infinite;
}
@keyframes pulse {
  0%,100%{opacity:1;}
  50%{opacity:0.7;}
}

/* Red text in notes */
.notes-red {
  color:#dc2626;
  font-weight:600;
}

/* Checkbox label */
.checkbox-label {
  display:flex !important;
  align-items:center;
  gap:8px;
  cursor:pointer;
  font-size:0.9rem !important;
  color:var(--text) !important;
}
.checkbox-label input[type=checkbox] {
  width:18px;
  height:18px;
  accent-color:var(--primary);
}

/* Inline blank inputs for fill questions */
.blank-input {
  display:inline-block;
  min-width:80px;
  max-width:200px;
  padding:4px 8px;
  border:none;
  border-bottom:2px dashed var(--danger);
  background:rgba(239,68,68,0.04);
  font-size:inherit;
  font-family:inherit;
  color:var(--primary);
  font-weight:600;
  text-align:center;
  outline:none;
  transition:border-color 0.2s,background 0.2s;
  margin:0 3px;
}
.blank-input:focus {
  border-bottom-color:var(--primary);
  background:rgba(79,70,229,0.06);
}
.blank-input::placeholder {
  color:#cbd5e1;
  font-weight:400;
}

/* Correct answer in feedback */
.blank-correct {
  display:inline-block;
  padding:2px 8px;
  border-radius:4px;
  background:rgba(16,185,129,0.15);
  color:#065f46;
  font-weight:700;
  margin:0 3px;
}

/* Reveal options button */
.btn-reveal {
  width:100%;
  padding:14px;
  border:2px dashed var(--primary);
  border-radius:10px;
  background:rgba(79,70,229,0.04);
  color:var(--primary);
  font-size:1rem;
  font-weight:600;
  cursor:pointer;
  transition:all 0.2s;
}
.btn-reveal:hover {
  background:rgba(79,70,229,0.1);
  border-style:solid;
}