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

body{font-family:-apple-system,BlinkMacSystemFont,"PingFang HK","Microsoft JhengHei","Segoe UI",sans-serif;background:#f5f7fa;min-height:100vh;-webkit-font-smoothing:antialiased}

/* Banner */
.banner{background:linear-gradient(135deg,#e74c3c 0%,#c0392b 50%,#a93226 100%);color:white;padding:24px 60px 24px 24px;text-align:center;border-radius:0 0 24px 24px;box-shadow:0 8px 24px rgba(231,76,60,.25);position:relative;display:flex;flex-direction:column;align-items:center;gap:8px;overflow:hidden}
.banner::before{content:"";position:absolute;top:-40%;right:-20%;width:300px;height:300px;background:rgba(255,255,255,.06);border-radius:50%}
.banner::after{content:"";position:absolute;bottom:-60%;left:-10%;width:200px;height:200px;background:rgba(255,255,255,.04);border-radius:50%}
.banner h1{margin:0;font-size:1.6rem;font-weight:700;letter-spacing:.5px;position:relative;z-index:1}
@media (max-width:480px){.banner h1{font-size:1.25rem}}
.banner p{margin:4px 0 0;opacity:.88;font-size:.95rem;position:relative;z-index:1}
.banner .btn-group{position:absolute;right:16px;top:50%;transform:translateY(-50%);display:flex;gap:8px;margin:0;z-index:1}
.banner .btn-group button{background:rgba(255,255,255,.18);border:none;color:white;padding:8px 14px;border-radius:10px;cursor:pointer;font-size:1rem;backdrop-filter:blur(8px);transition:all .2s}
.banner .btn-group button:hover{background:rgba(255,255,255,.3);transform:scale(1.05)}
@media (max-width:480px){.banner{padding:14px 16px;flex-direction:row;justify-content:space-between;align-items:center;border-radius:0 0 16px 16px}.banner h1{font-size:1.15rem;margin:0;text-align:left}.banner p{display:none}.banner .btn-group{position:static;transform:none;gap:6px;margin:0}.banner .btn-group button{padding:6px 10px;font-size:1rem}}

/* Container & screens */
.container{max-width:920px;margin:0 auto;padding:20px}
.screen{display:none;opacity:0;transform:translateY(12px);transition:opacity .3s ease,transform .3s ease}
.screen.active{display:block;opacity:1;transform:translateY(0)}

/* Card grid */
.card-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;margin-top:20px}

/* Chapter cards */
.chapter-card{background:white;border-radius:16px;padding:20px;cursor:pointer;box-shadow:0 1px 3px rgba(0,0,0,.06),0 4px 12px rgba(0,0,0,.04);transition:all .25s cubic-bezier(.4,0,.2,1);border:2px solid transparent;position:relative;overflow:hidden}
.chapter-card::before{content:"";position:absolute;left:0;top:0;width:4px;height:100%;background:linear-gradient(180deg,#e74c3c,#c0392b);opacity:0;transition:opacity .25s}
.chapter-card:hover{transform:translateY(-3px);border-color:#e74c3c;box-shadow:0 8px 24px rgba(231,76,60,.15)}
.chapter-card:hover::before{opacity:1}
.chapter-card.completed{border-color:#27ae60;background:linear-gradient(135deg,#eafaf1 0%,#e8f8f5 100%);box-shadow:0 1px 3px rgba(39,174,96,.08),0 4px 12px rgba(39,174,96,.06)}
.chapter-card.completed::before{background:linear-gradient(180deg,#27ae60,#1e8449)}
.chapter-card.completed:hover{border-color:#1e8449;box-shadow:0 8px 24px rgba(39,174,96,.2)}
.chapter-card.completed .ch-card-num{color:#27ae60}
.chapter-card .completed-badge{color:#27ae60;font-weight:700;margin-left:4px}
.ch-card-num{font-size:.72rem;font-weight:700;color:#e74c3c;text-transform:uppercase;letter-spacing:1.2px;margin-bottom:6px}
.ch-card-title{font-size:1.05rem;font-weight:600;color:#2c3e50;line-height:1.45}
.ch-card-q{font-size:.82rem;color:#95a5a6;margin-top:8px;font-weight:500}

/* Mode cards (home) */
.mode-card{background:white;border-radius:18px;padding:32px 24px;text-align:center;cursor:pointer;box-shadow:0 1px 3px rgba(0,0,0,.06),0 4px 12px rgba(0,0,0,.04);transition:all .3s cubic-bezier(.4,0,.2,1);border:2px solid transparent;position:relative;overflow:hidden}
.mode-card::after{content:"";position:absolute;bottom:0;left:0;width:100%;height:3px;background:linear-gradient(90deg,#e74c3c,#c0392b);opacity:0;transition:opacity .3s}
.mode-card:hover{transform:translateY(-4px);box-shadow:0 12px 28px rgba(0,0,0,.1)}
.mode-card:hover::after{opacity:1}
.mode-card .icon-wrap{width:56px;height:56px;border-radius:16px;display:flex;align-items:center;justify-content:center;margin:0 auto 16px;font-size:1.8rem;background:linear-gradient(135deg,#fff5f5 0%,#ffeaea 100%);box-shadow:0 2px 8px rgba(231,76,60,.1)}
.mode-card h2{font-size:1.2rem;margin:10px 0 6px;color:#2c3e50;font-weight:700;line-height:1.4}
.mode-card p{font-size:.85rem;color:#7f8c8d;margin-top:4px}

/* Buttons */
.back-btn{background:#fff;color:#2c3e50;border:1.5px solid #e1e8ed;padding:10px 20px;border-radius:12px;cursor:pointer;font-size:.9rem;margin-bottom:14px;font-weight:600;display:inline-flex;align-items:center;gap:6px;transition:all .2s;box-shadow:0 1px 3px rgba(0,0,0,.04)}
.back-btn:hover{background:#f8fafc;border-color:#cbd5e1;transform:translateX(-2px)}
.home-btn{background:#ecf0f1;color:#2c3e50;border:none;padding:10px 18px;border-radius:10px;cursor:pointer;font-size:.85rem;margin-bottom:14px;font-weight:600;display:inline-flex;align-items:center;gap:6px;transition:all .2s}
.home-btn:hover{background:#dfe6e9}

/* Progress bar */
.progress-bar{height:8px;background:#eef2f7;border-radius:4px;margin-bottom:20px;overflow:hidden;box-shadow:inset 0 1px 2px rgba(0,0,0,.05)}
.progress-fill{height:100%;background:linear-gradient(90deg,#e74c3c,#c0392b);border-radius:4px;transition:width .4s cubic-bezier(.4,0,.2,1);box-shadow:0 0 8px rgba(231,76,60,.2)}

/* Quiz */
.question-counter{text-align:center;font-size:.88rem;color:#7f8c8d;margin-bottom:16px;font-weight:500}
.quiz-card{background:white;border-radius:18px;padding:28px;box-shadow:0 1px 3px rgba(0,0,0,.06),0 8px 20px rgba(0,0,0,.04)}
.question-text{display:flex;align-items:flex-start;justify-content:space-between;font-size:1.15rem;font-weight:600;color:#2c3e50;line-height:1.75;margin-bottom:24px;padding-bottom:16px;border-bottom:1.5px solid #f0f3f7}

/* Options */
.option-btn{width:100%;padding:16px 20px;border:2px solid #eef2f7;border-radius:14px;background:white;text-align:left;font-size:1rem;cursor:pointer;transition:all .18s;margin-bottom:14px;color:#2c3e50;font-weight:500;display:flex;align-items:center;gap:10px}
.option-btn:hover{border-color:#e74c3c;background:linear-gradient(135deg,#fffafa 0%,#fff5f5 100%);transform:translateX(3px)}
.option-btn.correct{border-color:#27ae60;background:linear-gradient(135deg,#f0fdf4 0%,#eafaf1 100%);color:#27ae60;font-weight:700}
.option-btn.wrong{border-color:#e74c3c;background:linear-gradient(135deg,#fffafa 0%,#fdf2f1 100%);color:#e74c3c}
.option-btn.selected{border-color:#3498db;background:linear-gradient(135deg,#f0f9ff 0%,#ebf5fb 100%);color:#2980b9;font-weight:700}
.option-btn:disabled{cursor:default;opacity:.7}
.option-btn .opt-letter{width:28px;height:28px;border-radius:8px;background:#f8fafc;display:flex;align-items:center;justify-content:center;font-size:.8rem;font-weight:700;color:#7f8c8d;flex-shrink:0;transition:all .18s;border:1.5px solid #eef2f7}
.option-btn:hover .opt-letter{background:#fdf2f1;color:#e74c3c;border-color:#fadbd8}
.option-btn.correct .opt-letter{background:#eafaf1;color:#27ae60;border-color:#a3e9bf}
.option-btn.wrong .opt-letter{background:#fdf2f1;color:#e74c3c;border-color:#fadbd8}
.option-btn.selected .opt-letter{background:#ebf5fb;color:#3498db;border-color:#aed6f1}

/* Navigation */
.nav-row{display:flex;justify-content:space-between;align-items:center;margin-top:24px;gap:12px}
.nav-btn{padding:13px 24px;border:none;border-radius:14px;font-size:.95rem;font-weight:600;cursor:pointer;flex:1;text-align:center;transition:all .2s;box-shadow:0 2px 6px rgba(0,0,0,.08)}
.nav-btn.primary{background:linear-gradient(135deg,#e74c3c,#c0392b);color:white}
.nav-btn.primary:hover{background:linear-gradient(135deg,#c0392b,#a93226);transform:translateY(-1px);box-shadow:0 4px 12px rgba(231,76,60,.25)}
.nav-btn.secondary{background:#f0f2f5;color:#2c3e50}
.nav-btn.secondary:hover{background:#e1e5ea;transform:translateY(-1px)}

/* Results */
.result-box{background:white;border-radius:18px;padding:32px;text-align:center;box-shadow:0 1px 3px rgba(0,0,0,.06),0 8px 20px rgba(0,0,0,.04)}
.result-title{font-size:1.5rem;font-weight:700;margin-bottom:10px;color:#2c3e50}
.result-score{font-size:3rem;font-weight:800;color:#e74c3c;margin:20px 0;background:linear-gradient(135deg,#e74c3c,#c0392b);-webkit-background-clip:text;-webkit-text-fill-color:transparent}
.result-detail{font-size:.92rem;color:#7f8c8d;margin-bottom:24px}

/* Badges */
.mode-badge{display:inline-block;padding:5px 14px;border-radius:20px;font-size:.78rem;font-weight:700;margin-bottom:12px;letter-spacing:.3px}
.mode-badge.practice{background:#e8f8f5;color:#1e8449}
.mode-badge.quiz{background:#fef5e7;color:#b7791f}
.mode-badge.exam{background:#eafafe;color:#2471a3}
.mode-badge.mistake{background:#fdebd0;color:#b7791f}

/* Dark mode */
.dark body{background:#0f172a;color:#e2e8f0}
.dark .banner{background:linear-gradient(135deg,#1e3a5f 0%,#0f172a 50%,#1e293b 100%);box-shadow:0 8px 24px rgba(0,0,0,.3)}
.dark .chapter-card,.dark .mode-card,.dark .quiz-card,.dark .result-box{background:#1e293b;color:#e2e8f0;box-shadow:0 1px 3px rgba(0,0,0,.2),0 4px 12px rgba(0,0,0,.15)}
.dark .ch-card-title{color:#f1f5f9}
.dark .question-text{color:#f1f5f9;border-color:#334155}
.dark .option-btn{color:#e2e8f0;border-color:#334155;background:#1e293b}
.dark .option-btn:hover{border-color:#e74c3c;background:linear-gradient(135deg,#2d1b1b 0%,#1e293b 100%)}
.dark .nav-btn.secondary{background:#334155;color:#e2e8f0}
.dark .nav-btn.secondary:hover{background:#475569}
.dark .progress-bar{background:#334155}
.dark .back-btn{background:#1e293b;color:#e2e8f0;border-color:#334155}
.dark .back-btn:hover{background:#334155}
.dark .home-btn{background:#334155;color:#e2e8f0}
.dark .home-btn:hover{background:#475569}
.dark .mode-card .icon-wrap{background:linear-gradient(135deg,#2d1b1b 0%,#1e293b 100%);box-shadow:0 2px 8px rgba(0,0,0,.2)}
.dark .mode-card h2{color:#f1f5f9}

/* Scrollbar */
::-webkit-scrollbar{width:8px}
::-webkit-scrollbar-track{background:transparent}
::-webkit-scrollbar-thumb{background:#cbd5e1;border-radius:4px}
::-webkit-scrollbar-thumb:hover{background:#94a3b8}
.dark ::-webkit-scrollbar-thumb{background:#475569}
.dark ::-webkit-scrollbar-thumb:hover{background:#64748b}

/* Focus mode - reduces distractions during quiz */
.quiz-focus .banner{display:none}
.quiz-focus .home-btn{display:none}
.quiz-focus #keyboard-hint{display:none}
.quiz-focus .progress-bar{display:none}
.quiz-focus .container{padding-top:24px}
.quiz-focus .quiz-card{max-width:720px;margin:0 auto;box-shadow:0 1px 3px rgba(0,0,0,.04),0 4px 12px rgba(0,0,0,.02);border:1px solid #e2e8f0}
.quiz-focus .question-text{font-size:1.25rem;line-height:1.85;padding-bottom:24px;margin-bottom:28px}
.quiz-focus .option-btn{margin-bottom:16px;padding:18px 22px;font-size:1.05rem}
.quiz-focus .question-counter{margin-top:8px;font-size:.9rem;color:#94a3b8}

/* Calm theme - reduces anxiety with cool desaturated colors */
.calm .banner{background:linear-gradient(135deg,#475569 0%,#334155 50%,#1e293b 100%);box-shadow:0 4px 12px rgba(0,0,0,.1)}
.calm .nav-btn.primary{background:linear-gradient(135deg,#0d9488,#0f766e)}
.calm .nav-btn.primary:hover{background:linear-gradient(135deg,#0f766e,#115e59);box-shadow:0 4px 12px rgba(13,148,136,.2)}
.calm .progress-fill{background:linear-gradient(90deg,#0d9488,#0f766e);box-shadow:0 0 8px rgba(13,148,136,.15)}
.calm .option-btn:hover{border-color:#0d9488;background:linear-gradient(135deg,#f0fdfa 0%,#ecfeff 100%)}
.calm .option-btn:hover .opt-letter{background:#ecfeff;color:#0d9488;border-color:#a5f3fc}
.calm .chapter-card:hover{border-color:#0d9488;box-shadow:0 8px 24px rgba(13,148,136,.12)}
.calm .chapter-card::before{background:linear-gradient(180deg,#0d9488,#0f766e)}
.calm .mode-card:hover::after{background:linear-gradient(90deg,#0d9488,#0f766e);opacity:1}
.calm .mode-card .icon-wrap{background:linear-gradient(135deg,#f0fdfa 0%,#ecfeff 100%);box-shadow:0 2px 8px rgba(13,148,136,.08)}
.calm .ch-card-num{color:#0d9488}

/* Dark + calm */
.dark.calm .banner{background:linear-gradient(135deg,#1e3a5f 0%,#0f172a 50%,#1e293b 100%)}
.dark.calm .nav-btn.primary{background:linear-gradient(135deg,#14b8a6,#0d9488)}
.dark.calm .nav-btn.primary:hover{background:linear-gradient(135deg,#0d9488,#0f766e)}
.dark.calm .progress-fill{background:linear-gradient(90deg,#14b8a6,#0d9488);box-shadow:0 0 8px rgba(20,184,166,.15)}
.dark.calm .option-btn:hover{border-color:#14b8a8;background:linear-gradient(135deg,#134e4a 0%,#1e293b 100%)}
.dark.calm .option-btn:hover .opt-letter{background:#134e4a;color:#5eead4;border-color:#2dd4bf}
.dark.calm .mode-card .icon-wrap{background:linear-gradient(135deg,#134e4a 0%,#1e293b 100%);box-shadow:0 2px 8px rgba(0,0,0,.2)}

/* Quiz timer */
.quiz-timer{text-align:center;font-size:.85rem;color:#7f8c8d;margin-bottom:12px;font-weight:500;font-variant-numeric:tabular-nums}
.dark .quiz-timer{color:#94a3b8}
/* Streak feedback */
.streak-feedback{text-align:center;margin-bottom:14px;padding:8px 16px;border-radius:12px;font-size:.9rem;font-weight:600;display:inline-block;animation:streakPop .4s cubic-bezier(.4,0,.2,1)}
.streak-feedback.streak-3{background:#fef5e7;color:#d35400}
.streak-feedback.streak-5{background:#eafaf1;color:#1e8449;border:1px solid #a3e9bf}
.streak-feedback.streak-10{background:#e8f8f5;color:#1e8449;border:2px solid #27ae60;box-shadow:0 2px 8px rgba(39,174,96,.15)}
@keyframes streakPop{0%{transform:scale(.8);opacity:0}50%{transform:scale(1.05)}100%{transform:scale(1);opacity:1}}
.calm .streak-feedback.streak-5{background:#f0fdfa;color:#0f766e;border-color:#5eead4}
.calm .streak-feedback.streak-10{background:#ccfbf1;color:#0f766e;border-color:#14b8a6;box-shadow:0 2px 8px rgba(13,148,136,.15)}


/* 朗讀按鈕 */
.speak-btn {
  background: #f0f4f8;
  border: none;
  border-radius: 50%;
  width: 36px;
  height: 36px;
  font-size: 1.1rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: all .2s;
  flex-shrink: 0;
  margin-left: 10px;
}
.speak-btn:hover {
  background: #e1eaf3;
  transform: scale(1.1);
}
.speak-btn.speaking {
  background: #3498db;
  color: white;
}
.speak-btn.speaking:hover {
  background: #2980b9;
}

/* 朗讀速度滑塊 */
#speakRateSlider {
  -webkit-appearance: none;
  appearance: none;
  height: 6px;
  background: #ecf0f1;
  border-radius: 3px;
  outline: none;
}
#speakRateSlider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  background: #3498db;
  border-radius: 50%;
  cursor: pointer;
  transition: transform .15s;
}
#speakRateSlider::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}
#speakRateSlider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  background: #3498db;
  border-radius: 50%;
  cursor: pointer;
  border: none;
}