:root {
  --ink: #223233;
  --muted: #5d6a68;
  --paper: #fbfaf4;
  --panel: #ffffff;
  --teal: #00756f;
  --teal-dark: #084c49;
  --mint: #d9eee8;
  --amber: #f3b23b;
  --coral: #e85d44;
  --line: rgba(34, 50, 51, 0.14);
  --shadow: 0 18px 42px rgba(21, 41, 38, 0.12);
}

* { box-sizing: border-box; }

html, body {
  width: 100%;
  margin: 0;
  padding: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans TC", "PingFang TC", sans-serif;
}

body {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

.app { flex: 1; display: flex; flex-direction: column; }

/* 基礎 Screen 設定 */
.screen {
  position: relative;
  min-height: 100dvh;
  padding: clamp(20px, 4vw, 56px);
  display: flex;
  flex-direction: column;
}

.screen::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: clamp(10px, 1.2vw, 20px);
  background: var(--teal);
}

/* 內容區塊 */
.content {
  flex: 1 0 auto;
  width: min(1180px, 100%);
  margin: 0 auto;
  padding-bottom: 120px; /* 預留給 Sticky Footer 的空間 */
  display: flex;
  flex-direction: column;
  justify-content: center;
}

/* --- Sticky Footer 解決方案 --- */
.actions {
  position: sticky;
  bottom: 0;
  z-index: 1000;
  background: var(--paper);
  padding: 20px 40px 40px 40px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: flex-end;
  gap: 14px;
  margin: 0 -56px -56px -56px; /* 貼齊螢幕邊緣 */
  box-shadow: 0 -10px 30px rgba(0,0,0,0.05);
}

/* 首頁不使用 Sticky，保持大氣 */
.home .actions {
  position: relative;
  background: transparent;
  border: 0;
  box-shadow: none;
  justify-content: center;
  padding: 0;
  margin: 40px 0 0 0;
}

.home .content {
  padding-bottom: 0;
  text-align: center;
}

/* 文字樣式回歸 */
h1 { font-size: clamp(56px, 10vw, 96px); line-height: 0.95; margin: 28px 0; font-weight: 950; }
h2 { font-size: clamp(32px, 5vw, 46px); line-height: 1.08; margin-bottom: 24px; font-weight: 900; }
.lead { color: var(--muted); font-size: clamp(20px, 3vw, 31px); line-height: 1.42; font-weight: 700; max-width: 800px; margin: 0 auto 30px; }

.badge {
  display: inline-flex;
  padding: 10px 20px;
  border: 2px solid var(--teal);
  color: var(--teal-dark);
  background: var(--mint);
  border-radius: 999px;
  font-size: clamp(16px, 2vw, 22px);
  font-weight: 800;
  margin-bottom: 10px;
}

.topbar { display: flex; align-items: center; justify-content: space-between; margin-bottom: 30px; }
.step { color: var(--teal-dark); font-size: 20px; font-weight: 900; }

/* 按鈕樣式回歸 */
.primary-button, .secondary-button, .quiet-button {
  min-height: 62px;
  border: 0;
  border-radius: 8px;
  padding: 0 32px;
  cursor: pointer;
  font-size: 22px;
  font-weight: 900;
  transition: transform 0.1s;
}
.primary-button { color: #fff; background: var(--teal); box-shadow: 0 10px 24px rgba(0, 117, 111, 0.22); }
.secondary-button { color: var(--ink); background: var(--amber); }
.quiet-button { color: var(--teal-dark); background: transparent; border: 2px solid var(--line); }
.primary-button:active { transform: translateY(2px); }

/* 書籍網格：強制四本一排 */
.book-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.book-button {
  background: var(--panel);
  border-radius: 12px;
  padding: 15px;
  border: 2px solid transparent;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 12px;
  cursor: pointer;
  text-align: left;
}

.book-image-wrap { 
  aspect-ratio: 1/1.2; 
  background: #eef5f2; 
  border-radius: 6px; 
  overflow: hidden; 
  display: flex;
  align-items: center;
  justify-content: center;
}
.book-image-wrap img { width: 100%; height: 100%; object-fit: contain; }
.book-title { font-size: 19px; font-weight: 900; line-height: 1.2; min-height: 46px; display: flex; align-items: center; }

/* 策略清單回歸 */
.strategy-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; margin-top: 20px; }
.strategy-item {
  display: flex;
  gap: 14px;
  padding: 18px;
  border-left: 8px solid var(--amber);
  background: rgba(255, 255, 255, 0.8);
  box-shadow: 0 1px 0 var(--line);
}
.strategy-number { width: 40px; height: 40px; flex-shrink: 0; background: var(--teal); color: #fff; border-radius: 50%; display: grid; place-items: center; font-weight: 900; font-size: 18px; }
.strategy-text strong { display: block; font-size: 22px; margin-bottom: 4px; }
.strategy-text span { font-size: 17px; color: var(--muted); }

/* 準備與測驗佈局回歸 */
.ready-layout, .quiz-layout {
  display: grid;
  grid-template-columns: 0.4fr 1fr;
  gap: 50px;
  align-items: center;
}

.selected-cover, .mini-cover {
  background: #eef5f2;
  border-radius: 12px;
  box-shadow: var(--shadow);
  overflow: hidden;
  max-width: 100%;
}
.selected-cover img, .mini-cover img { width: 100%; display: block; object-fit: contain; }

/* 錯題解析回歸 */
.miss-list { display: grid; gap: 14px; margin-top: 20px; }
.miss-item {
  padding: 18px;
  border-left: 8px solid var(--coral);
  background: #fff;
  box-shadow: 0 1px 0 var(--line);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.miss-item strong { font-size: 20px; }
.miss-item span { font-size: 17px; color: var(--muted); }

/* 評分與統計回歸 */
.stars { display: flex; justify-content: center; gap: 15px; margin: 30px 0; }
.star-btn { background: none; border: none; font-size: 64px; color: #ddd; cursor: pointer; transition: 0.2s; }
.star-btn.active { color: var(--amber); transform: scale(1.1); }

.stat-row { background: #fff; padding: 20px; border-radius: 12px; box-shadow: 0 4px 12px rgba(0,0,0,0.05); margin-bottom: 16px; }
.stat-info { display: flex; justify-content: space-between; font-weight: 900; font-size: 20px; margin-bottom: 10px; }
.stat-bar-bg { height: 24px; background: var(--mint); border-radius: 12px; overflow: hidden; }
.stat-bar-fill { height: 100%; background: var(--teal); transition: width 1s ease-out; }

/* 計時頁面佈局 */
.timer-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: center;
}

.timer-zone {
  text-align: center;
  background: var(--panel);
  padding: 30px;
  border-radius: 16px;
  box-shadow: var(--shadow);
}

.timer-display {
  font-size: clamp(80px, 10vw, 120px);
  font-weight: 950;
  color: var(--teal-dark);
  line-height: 1;
  margin: 10px 0;
}

.strategy-list.compact {
  grid-template-columns: 1fr;
  gap: 10px;
}

.strategy-item.compact {
  padding: 10px 15px;
  border-left-width: 4px;
}

.strategy-item.compact .strategy-number {
  width: 24px;
  height: 24px;
  font-size: 14px;
}

.strategy-item.compact .strategy-text strong {
  font-size: 17px;
  margin-bottom: 0;
}

@media (max-width: 900px) {
  .timer-layout {
    grid-template-columns: 1fr;
    gap: 20px;
  }
}

/* 響應式：平板小螢幕與手機 */
@media (max-width: 900px) {
  .book-grid { grid-template-columns: repeat(2, 1fr); }
  .ready-layout, .quiz-layout { grid-template-columns: 1fr; gap: 20px; }
  .selected-cover { max-height: 300px; }
  .strategy-list { grid-template-columns: 1fr; }
}

@media (max-width: 600px) {
  .actions { flex-direction: column; padding: 15px 20px 25px 20px; }
  .primary-button, .secondary-button, .quiet-button { width: 100%; }
}