:root {
  --accent: #ff6b35;
  --accent-dark: #e85a2b;
  --accent2: #00b4d8;
  --success: #00b894;
  --danger: #ff4757;
  --warning: #ffd166;
  --bg: #0d1b2a;
  --card: rgba(255,255,255,0.08);
  --border: rgba(255,255,255,0.12);
  --text: #ffffff;
  --muted: #b0bec5;
}

* { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  width: 100%; height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: linear-gradient(180deg, #0d1b2a 0%, #1b2838 50%, #1a237e 100%);
  color: var(--text);
  overflow-x: hidden;
}

.app {
  width: 100%; max-width: 560px;
  margin: 0 auto; padding: 20px;
  min-height: 100%;
  display: flex; flex-direction: column;
}

.game-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 18px;
  flex-wrap: wrap; gap: 8px;
}
.game-header h1 {
  font-size: 22px; margin: 0;
  background: linear-gradient(90deg, var(--warning), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
.back-link {
  color: var(--muted); text-decoration: none; font-size: 13px;
}
.back-link:hover { color: #fff; }
.subject-badge {
  font-size: 12px; font-weight: 700;
  padding: 4px 12px; border-radius: 50px;
  background: rgba(255,215,0,0.12);
  color: var(--warning); border: 1px solid rgba(255,215,0,0.35);
}

.screen { display: none; flex-direction: column; flex: 1; }
.screen.active { display: flex; }

/* ===== 开始界面 ===== */
#startScreen { text-align: center; padding-top: 10px; }
.hero-emoji { font-size: 56px; margin-bottom: 12px; }
#startScreen h2 { font-size: 26px; margin: 0 0 8px; }
.hero-desc { color: var(--muted); font-size: 14px; margin-bottom: 22px; line-height: 1.6; }

.mode-select {
  display: flex; flex-direction: column; gap: 12px;
  margin-bottom: 22px;
}
.mode-card {
  display: block;
  background: var(--card); border: 2px solid var(--border);
  border-radius: 16px; padding: 16px;
  cursor: pointer; transition: all .2s;
  text-align: left; color: #fff;
}
.mode-card:hover, .mode-card.active {
  border-color: var(--accent);
  background: rgba(255,107,53,0.12);
}
.mode-card input { display: none; }
.mode-title { font-size: 17px; font-weight: 700; margin-bottom: 4px; }
.mode-desc { font-size: 13px; color: var(--muted); }

.subject-select { margin-bottom: 22px; }
.select-label { font-size: 13px; color: var(--muted); margin-bottom: 10px; }
.subject-chips {
  display: flex; gap: 10px; justify-content: center; flex-wrap: wrap;
}
.subject-chip {
  background: var(--card); border: 2px solid var(--border);
  color: #fff; padding: 10px 16px; border-radius: 50px;
  cursor: pointer; font-size: 14px; font-weight: 600;
  transition: all .2s;
}
.subject-chip:hover, .subject-chip.active {
  border-color: var(--accent2);
  background: rgba(0,180,216,0.18);
}

.chapter-select { margin-bottom: 22px; }
.chapter-mode {
  display: flex; gap: 10px; justify-content: center; margin-bottom: 12px;
}
.chapter-mode-btn {
  flex: 1; max-width: 140px;
  background: var(--card); border: 2px solid var(--border);
  color: #fff; padding: 10px; border-radius: 12px;
  cursor: pointer; font-size: 13px; font-weight: 600;
  transition: all .2s;
}
.chapter-mode-btn:hover, .chapter-mode-btn.active {
  border-color: var(--accent);
  background: rgba(255,107,53,0.12);
}
.chapter-list {
  display: flex; flex-wrap: wrap; gap: 8px;
  justify-content: center; max-height: 150px; overflow-y: auto;
  padding: 10px; background: rgba(0,0,0,0.15);
  border-radius: 14px; border: 1px solid var(--border);
  margin-bottom: 8px;
}
.chapter-tag {
  background: var(--card); border: 2px solid var(--border);
  color: #fff; padding: 8px 12px; border-radius: 50px;
  cursor: pointer; font-size: 12px; font-weight: 600;
  transition: all .2s; user-select: none;
}
.chapter-tag:hover, .chapter-tag.active {
  border-color: var(--success);
  background: rgba(0,184,148,0.18);
}
.chapter-tag .check { opacity: 0; margin-right: 4px; }
.chapter-tag.active .check { opacity: 1; }
.chapter-tip {
  font-size: 12px; color: var(--muted);
  text-align: center;
}

.primary-btn {
  display: block; width: 100%;
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dark) 100%);
  color: #fff; border: none; border-radius: 50px;
  padding: 14px; font-size: 17px; font-weight: 700;
  cursor: pointer; box-shadow: 0 6px 18px rgba(255,107,53,0.35);
  transition: transform .2s, box-shadow .2s;
}
.primary-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 22px rgba(255,107,53,0.45); }

.wrong-bank-bar {
  margin-top: 16px;
  background: rgba(0,0,0,0.2);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 14px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.wrong-bank-info {
  font-size: 14px;
  color: var(--muted);
  text-align: left;
}
.wrong-bank-info b {
  color: var(--warning);
  font-size: 18px;
  margin: 0 4px;
}
#wrongBankBtn {
  width: auto;
  padding: 8px 16px;
  font-size: 14px;
  flex-shrink: 0;
}

/* ===== 战斗界面 ===== */
.battle-status {
  display: flex; gap: 8px; justify-content: center;
  margin-bottom: 16px; flex-wrap: wrap;
}
.status-pill {
  background: rgba(0,0,0,0.25);
  padding: 6px 12px; border-radius: 50px;
  font-size: 13px; color: var(--muted);
}
.status-pill b { color: #fff; }

.arena {
  display: flex; align-items: flex-end; justify-content: space-between;
  gap: 10px; margin-bottom: 20px;
  padding: 16px; background: rgba(0,0,0,0.18);
  border-radius: 20px;
}
.fighter { flex: 1; text-align: center; }
.fighter-area { position: relative; height: 84px; margin-bottom: 8px; }
.fighter-emoji {
  font-size: 56px; line-height: 84px;
  display: inline-block; transition: transform .2s;
  filter: drop-shadow(0 6px 12px rgba(0,0,0,0.35));
}
.fighter-emoji.hurt { animation: hurt .4s; }
.fighter-emoji.attack { animation: attack .3s; }
.fighter-emoji.defeated { animation: defeated .9s forwards; }
.fighter-emoji.appear { animation: appear .55s; }
@keyframes hurt {
  0%,100% { transform: translateX(0); }
  25% { transform: translateX(-10px) rotate(-5deg); }
  75% { transform: translateX(10px) rotate(5deg); }
}
@keyframes attack {
  0%,100% { transform: translateX(0); }
  50% { transform: translateX(16px) scale(1.1); }
}
@keyframes defeated {
  0% { transform: rotate(0) scale(1); opacity: 1; }
  30% { transform: rotate(-12deg) scale(1.08); }
  60% { transform: rotate(70deg) scale(0.85) translateY(12px); opacity: 0.6; filter: grayscale(0.5); }
  100% { transform: rotate(90deg) scale(0.5) translateY(36px); opacity: 0; filter: grayscale(1); }
}
@keyframes appear {
  0% { transform: scale(0) translateY(-28px) rotate(-180deg); opacity: 0; }
  60% { transform: scale(1.25) translateY(0) rotate(10deg); opacity: 1; }
  100% { transform: scale(1) translateY(0) rotate(0); opacity: 1; }
}
.fighter-name { font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.hp-bar {
  height: 12px; background: rgba(0,0,0,0.35);
  border-radius: 50px; overflow: hidden;
  border: 1px solid rgba(255,255,255,0.15);
}
.hp-fill { height: 100%; border-radius: 50px; transition: width .6s ease; }
.hp-fill.player { background: linear-gradient(90deg, var(--accent2), #74b9ff); }
.hp-fill.monster { background: linear-gradient(90deg, var(--danger), var(--accent)); }
.hp-text { font-size: 11px; color: var(--muted); margin-top: 4px; }
.vs {
  font-size: 16px; font-weight: 800; color: var(--warning);
  align-self: center; padding-bottom: 26px;
}

.effect {
  position: absolute; left: 50%; top: 20px;
  transform: translateX(-50%); opacity: 0; pointer-events: none;
}
.beam {
  width: 6px; height: 60px; border-radius: 3px;
  background: linear-gradient(var(--accent2), transparent);
}
.beam.monster-beam { background: linear-gradient(var(--danger), transparent); }
.beam.fire { animation: beamShoot .35s; }
@keyframes beamShoot {
  0% { opacity: 1; height: 0; }
  50% { opacity: 1; height: 80px; }
  100% { opacity: 0; height: 110px; }
}
.damage-number {
  position: absolute; left: 50%; top: 0;
  transform: translateX(-50%); font-weight: 800; font-size: 18px;
  color: var(--warning); opacity: 0; pointer-events: none;
}
.damage-number.show { animation: floatUp .8s forwards; }
@keyframes floatUp {
  0% { opacity: 1; transform: translateX(-50%) translateY(0); }
  100% { opacity: 0; transform: translateX(-50%) translateY(-36px); }
}

.question-box {
  background: rgba(0,0,0,0.25);
  border-radius: 16px; padding: 16px;
  margin-bottom: 14px; min-height: 90px;
}
.question-tag {
  display: inline-block; background: var(--accent);
  color: #fff; font-size: 11px; font-weight: 700;
  padding: 3px 10px; border-radius: 50px; margin-bottom: 8px;
}
.question-text { font-size: 16px; line-height: 1.65; }

.options {
  display: grid; grid-template-columns: 1fr 1fr; gap: 10px;
}
.option-btn {
  background: var(--card); border: 2px solid var(--border);
  color: #fff; padding: 12px; border-radius: 12px;
  cursor: pointer; font-size: 14px; text-align: center;
  transition: all .2s;
}
.option-btn:hover:not(:disabled) {
  background: rgba(255,255,255,0.14); transform: translateY(-2px);
}
.option-btn.correct { background: var(--success); border-color: var(--success); }
.option-btn.wrong { background: var(--danger); border-color: var(--danger); }
.option-btn:disabled { opacity: .7; cursor: not-allowed; }

.feedback {
  text-align: center; min-height: 28px; line-height: 28px;
  font-weight: 700; font-size: 14px; margin-top: 12px;
}
.feedback.good { color: var(--success); }
.feedback.bad { color: var(--danger); }

.hint-area {
  margin-top: 14px;
  display: flex; flex-direction: column; gap: 10px;
  align-items: center;
}
.hint-text {
  background: rgba(0,0,0,0.25);
  border-left: 4px solid var(--accent2);
  padding: 12px 14px; border-radius: 10px;
  font-size: 14px; line-height: 1.6; color: #fff;
  width: 100%;
}
.hint-btn {
  background: linear-gradient(135deg, var(--accent2) 0%, #0077b6 100%);
  color: #fff; border: none; border-radius: 50px;
  padding: 10px 20px; font-size: 14px; font-weight: 700;
  cursor: pointer; box-shadow: 0 4px 12px rgba(0,180,216,0.3);
  transition: transform .2s;
}
.hint-btn:hover:not(:disabled) { transform: translateY(-2px); }
.hint-btn:disabled {
  background: rgba(255,255,255,0.12);
  color: var(--muted); cursor: not-allowed; box-shadow: none;
}
.next-btn {
  background: rgba(255,255,255,0.1);
  color: #fff; border: 2px solid rgba(255,255,255,0.2);
  border-radius: 50px; padding: 8px 18px;
  font-size: 13px; font-weight: 700; cursor: pointer;
  transition: all .2s;
}
.next-btn:hover { background: rgba(255,255,255,0.18); }

/* ===== 结算界面 ===== */
#resultScreen { text-align: center; padding-top: 20px; }
.result-emoji { font-size: 60px; margin-bottom: 12px; }
#resultScreen h2 { font-size: 26px; margin: 0 0 8px; }
.result-desc { color: var(--muted); font-size: 14px; margin-bottom: 22px; }
.result-stats {
  display: flex; gap: 12px; justify-content: center;
  flex-wrap: wrap; margin-bottom: 26px;
}
.result-stat {
  background: rgba(0,0,0,0.25); border-radius: 14px;
  padding: 14px 18px; min-width: 90px;
}
.result-stat .num { font-size: 24px; font-weight: 800; color: var(--warning); }
.result-stat .label { font-size: 12px; color: var(--muted); }
.result-actions { display: flex; flex-direction: column; gap: 12px; }
.secondary-btn {
  display: block; width: 100%;
  background: transparent; border: 2px solid var(--border);
  color: #fff; border-radius: 50px;
  padding: 12px; font-size: 15px; font-weight: 700;
  text-decoration: none; text-align: center;
  cursor: pointer; transition: all .2s;
}
.secondary-btn:hover { background: rgba(255,255,255,0.08); }

@media (max-width: 400px) {
  .options { grid-template-columns: 1fr; }
  .arena { padding: 12px; }
  .fighter-emoji { font-size: 46px; }
}