:root {
  --bg-primary: #f8f3e6;
  --card-bg: #fff8eb;
  --card-border: #c9a24b;
  --text-main: #3a3020;
  --text-muted: #7b694b;
  --title-color: #6a4614;
  --accent-gold: #c9a24b;
  --accent-hover: #b58d36;
  --tag-bg: #f2e4c4;
  --tag-text: #6d4b1a;
  --opt-border: #d4c5a6;
  --opt-bg: #ffffff;
  --opt-hover: #fefcf6;
  --correct-bg: #e2f4d6;
  --correct-border: #468c41;
  --correct-text: #1d4d1a;
  --wrong-bg: #fde8e8;
  --wrong-border: #d9534f;
  --wrong-text: #842029;
  --explanation-bg: #f4e8cf;
  --btn-main: #7b531e;
  --btn-main-text: #ffffff;
  --shadow-sm: 0 4px 12px rgba(90, 60, 20, 0.08);
  --shadow-lg: 0 12px 36px rgba(80, 50, 10, 0.14);
}

[data-theme="dark"] {
  --bg-primary: #191612;
  --card-bg: #24201a;
  --card-border: #8b6c2c;
  --text-main: #ecdcc3;
  --text-muted: #b09e82;
  --title-color: #e5be6b;
  --accent-gold: #c9a24b;
  --accent-hover: #deb356;
  --tag-bg: #383025;
  --tag-text: #e1b96a;
  --opt-border: #4d4233;
  --opt-bg: #2d261e;
  --opt-hover: #362e24;
  --correct-bg: #1e3a1c;
  --correct-border: #52a34b;
  --correct-text: #c2f0bb;
  --wrong-bg: #3d1c1e;
  --wrong-border: #c94747;
  --wrong-text: #f8c2c4;
  --explanation-bg: #322b22;
  --btn-main: #c9a24b;
  --btn-main-text: #191612;
  --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 36px rgba(0, 0, 0, 0.6);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang TC", "Microsoft JhengHei", sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-main);
  min-height: 100vh;
  min-height: -webkit-fill-available;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: env(safe-area-inset-top, 12px) 16px env(safe-area-inset-bottom, 20px);
  transition: background-color 0.3s ease, color 0.3s ease;
  user-select: none;
  -webkit-user-select: none;
}

.app-container {
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  flex: 1;
}

/* Header & Top Bar */
.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 4px 16px;
}

.brand-badge {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 16px;
  font-weight: 700;
  color: var(--title-color);
}

.star-counter {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 13px;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: 20px;
  border: 1px solid var(--card-border);
}

.top-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.icon-btn {
  background: var(--card-bg);
  border: 1px solid var(--opt-border);
  color: var(--text-main);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 16px;
  box-shadow: var(--shadow-sm);
}

/* Category Tabs (Levels) */
.level-nav-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 4px 6px;
}

.level-nav-title {
  font-size: 13px;
  font-weight: 700;
  color: var(--title-color);
}

.level-nav-hint {
  font-size: 12px;
  font-weight: 600;
  color: var(--accent-gold);
  background: var(--tag-bg);
  padding: 2px 8px;
  border-radius: 12px;
}

.level-nav {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  padding: 4px 2px 14px;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}
.level-nav::-webkit-scrollbar {
  display: none;
}

.level-chip {
  flex-shrink: 0;
  background: var(--card-bg);
  border: 1px solid var(--opt-border);
  color: var(--text-muted);
  font-size: 13px;
  font-weight: 600;
  padding: 7px 14px;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.level-chip.active {
  background: var(--accent-gold);
  border-color: var(--accent-gold);
  color: #fff;
  box-shadow: 0 2px 8px rgba(201, 162, 75, 0.4);
}

/* Drawer Book Selector */
.drawer-section-label {
  font-size: 12px;
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.drawer-books-bar {
  display: flex;
  gap: 6px;
  overflow-x: auto;
  padding: 2px 2px 10px;
  margin-bottom: 12px;
  border-bottom: 1px dashed var(--opt-border);
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

.drawer-books-bar::-webkit-scrollbar {
  display: none;
}

.drawer-book-chip {
  flex-shrink: 0;
  padding: 6px 11px;
  border-radius: 10px;
  font-size: 12px;
  font-weight: 700;
  background: var(--opt-bg);
  color: var(--text-muted);
  border: 1px solid var(--opt-border);
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.2s ease;
}

.drawer-book-chip.active {
  background: var(--accent-gold);
  color: #ffffff;
  border-color: var(--accent-gold);
  box-shadow: 0 2px 6px rgba(201, 162, 75, 0.35);
}

/* Chapter Progress Pill */
.chapter-status-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  padding: 0 4px;
}

.chapter-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
}

.progress-track {
  flex: 1;
  max-width: 140px;
  height: 6px;
  background: var(--opt-border);
  border-radius: 3px;
  overflow: hidden;
  margin-left: 12px;
}

.progress-fill {
  height: 100%;
  background: var(--accent-gold);
  border-radius: 3px;
  transition: width 0.3s ease;
}

/* Main Reading / Homework Card */
.homework-card {
  background: var(--card-bg);
  border: 2px solid var(--card-border);
  border-radius: 20px;
  padding: 22px 18px 20px;
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all 0.25s ease;
  min-height: 440px;
}

.card-header-badge {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.category-tag {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: var(--tag-text);
  background: var(--tag-bg);
  padding: 4px 10px;
  border-radius: 8px;
}

.card-title {
  font-size: 19px;
  font-weight: 800;
  color: var(--title-color);
  line-height: 1.45;
  margin-bottom: 14px;
}

/* Lesson Bite Content */
.lesson-box {
  margin-bottom: 18px;
}

.lesson-text {
  font-size: 16px;
  line-height: 1.75;
  color: var(--text-main);
  margin-bottom: 12px;
}

.lesson-tip {
  background: var(--tag-bg);
  border-left: 4px solid var(--accent-gold);
  border-radius: 0 10px 10px 0;
  padding: 10px 14px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--tag-text);
  margin: 10px 0 16px;
}

.code-snippet {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  background: rgba(0, 0, 0, 0.06);
  padding: 2px 6px;
  border-radius: 6px;
  font-weight: 600;
  color: var(--title-color);
}

/* Quiz Section */
.quiz-divider {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 12px 0 14px;
  color: var(--accent-gold);
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.quiz-divider::before,
.quiz-divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--opt-border);
}

.quiz-question {
  font-size: 16px;
  font-weight: 700;
  line-height: 1.55;
  color: var(--text-main);
  margin-bottom: 12px;
}

.options-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 16px;
}

.opt-btn {
  display: flex;
  align-items: flex-start;
  text-align: left;
  gap: 12px;
  padding: 12px 14px;
  border: 1.5px solid var(--opt-border);
  background: var(--opt-bg);
  border-radius: 12px;
  font-size: 15px;
  line-height: 1.5;
  color: var(--text-main);
  cursor: pointer;
  transition: all 0.18s ease;
  min-height: 48px;
}

.opt-btn:active {
  transform: scale(0.985);
}

.opt-btn .opt-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--tag-bg);
  color: var(--tag-text);
  font-size: 12px;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 1px;
}

/* Option Selected States */
.opt-btn.correct {
  background: var(--correct-bg) !important;
  border-color: var(--correct-border) !important;
  color: var(--correct-text) !important;
  box-shadow: 0 2px 12px rgba(70, 140, 65, 0.25);
}
.opt-btn.correct .opt-badge {
  background: var(--correct-border);
  color: #fff;
}

.opt-btn.wrong {
  background: var(--wrong-bg) !important;
  border-color: var(--wrong-border) !important;
  color: var(--wrong-text) !important;
  animation: shake 0.35s ease;
}
.opt-btn.wrong .opt-badge {
  background: var(--wrong-border);
  color: #fff;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-6px); }
  75% { transform: translateX(6px); }
}

/* Explanation Box */
.explanation-box {
  background: var(--explanation-bg);
  border-radius: 12px;
  padding: 14px 16px;
  font-size: 14px;
  line-height: 1.65;
  margin-bottom: 16px;
  border-left: 4px solid var(--correct-border);
  animation: fadeIn 0.25s ease;
}

.explanation-box.hint {
  border-left-color: var(--accent-gold);
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Footer / Action Controls */
.bottom-controls {
  display: flex;
  gap: 10px;
  margin-top: auto;
  padding-top: 10px;
}

.btn {
  flex: 1;
  min-height: 48px;
  padding: 10px 16px;
  border-radius: 12px;
  font-size: 15px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  transition: all 0.2s ease;
  border: none;
}

.btn-secondary {
  background: var(--tag-bg);
  color: var(--tag-text);
  border: 1px solid var(--card-border);
  max-width: 90px;
}

.btn-primary {
  background: var(--btn-main);
  color: var(--btn-main-text);
  box-shadow: 0 4px 14px rgba(123, 83, 30, 0.25);
}

.btn-primary:active {
  transform: scale(0.97);
}

/* Modal Drawer (Book Table of Contents) */
.drawer-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  z-index: 99;
  display: none;
}
.drawer-backdrop.show {
  display: block;
}

.drawer-content {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--card-bg);
  border-radius: 24px 24px 0 0;
  max-height: 80vh;
  padding: 20px 20px calc(24px + env(safe-area-inset-bottom, 20px));
  z-index: 100;
  display: flex;
  flex-direction: column;
  transform: translateY(100%);
  transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 -8px 30px rgba(0, 0, 0, 0.3);
}
.drawer-content.show {
  transform: translateY(0);
}

.drawer-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--opt-border);
  margin-bottom: 12px;
}

.drawer-title {
  font-size: 18px;
  font-weight: 800;
  color: var(--title-color);
}

.drawer-list {
  list-style: none;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.drawer-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 14px;
  border-radius: 12px;
  border: 1px solid var(--opt-border);
  background: var(--opt-bg);
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
}

.drawer-item.active {
  border-color: var(--accent-gold);
  background: var(--tag-bg);
  color: var(--title-color);
}

.drawer-item .item-stars {
  font-size: 13px;
  color: var(--accent-gold);
}

/* ── 我的筆記本／畫線（9/25）── */
.icon-btn { position: relative; }
.note-count:not(:empty) {
  position: absolute; top: -4px; right: -4px; min-width: 18px; height: 18px; padding: 0 4px;
  border-radius: 9px; background: var(--wrong-border); color: #fff; font-size: 11px; font-weight: 700;
  line-height: 18px; text-align: center;
}
#notebookList { overflow-y: auto; -webkit-overflow-scrolling: touch; }
.nb-actions { display: flex; gap: 10px; margin-bottom: 6px; }
.nb-actions .btn { flex: 1; }
.nb-hint { font-size: 13px; color: var(--text-muted); margin-bottom: 8px; }
.nb-section { font-weight: 700; color: var(--title-color); margin: 16px 0 8px; font-size: 15px; }
.nb-empty { font-size: 13px; color: var(--text-muted); padding: 4px 0 8px; }
.nb-item {
  background: var(--opt-bg); border: 1px solid var(--opt-border); border-radius: 12px;
  padding: 10px 12px; margin-bottom: 8px; font-size: 15px; line-height: 1.6; color: var(--text-main);
  overflow-wrap: anywhere;
}
.nb-item.done { opacity: 0.6; }
.nb-kind { font-size: 12px; color: var(--text-muted); margin-bottom: 2px; }
.nb-quote { border-left: 3px solid var(--accent-gold); padding-left: 8px; margin: 4px 0; }
.nb-wrong { color: var(--wrong-text); font-size: 14px; }
.nb-right { color: var(--correct-text); font-size: 14px; }
.nb-btns { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 8px; }
.nb-btns button, .nb-mini, .retry-btn {
  font: inherit; font-size: 13px; padding: 6px 12px; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--opt-border); background: var(--card-bg); color: var(--text-main);
}
.retry-btn { display: block; margin-top: 10px; }
.my-marks { margin-top: 14px; }
.quick-note { margin-top: 14px; }
.quick-note-label { font-size: 13px; color: var(--text-muted); margin-bottom: 6px; }
.quick-note textarea, .mark-sheet textarea {
  width: 100%; box-sizing: border-box; font: inherit; font-size: 16px; padding: 10px; border-radius: 12px;
  border: 1px solid var(--opt-border); background: var(--opt-bg); color: var(--text-main); resize: vertical;
}
.mark-kinds { display: flex; flex-wrap: wrap; gap: 8px; margin: 8px 0; }
.mark-kind {
  font: inherit; font-size: 14px; padding: 8px 12px; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--opt-border); background: var(--card-bg); color: var(--text-main);
}
.mark-kind.active { border-color: var(--accent-gold); background: var(--tag-bg); color: var(--tag-text); font-weight: 700; }
.mark-fab {
  position: fixed; left: 50%; transform: translateX(-50%);
  bottom: calc(84px + env(safe-area-inset-bottom, 0px)); z-index: 98;
  font: inherit; font-size: 16px; font-weight: 700; padding: 12px 20px; border-radius: 999px; border: none;
  background: var(--btn-main); color: var(--btn-main-text); box-shadow: var(--shadow-lg); cursor: pointer;
}
.mark-fab[hidden] { display: none; }
.mark-sheet {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 101; background: var(--card-bg);
  border-radius: 24px 24px 0 0; padding: 20px 20px calc(20px + env(safe-area-inset-bottom, 16px));
  transform: translateY(100%); transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 -8px 30px rgba(0, 0, 0, 0.3);
}
.mark-sheet.show { transform: translateY(0); }
.mark-quote {
  border-left: 3px solid var(--accent-gold); padding-left: 10px; margin-bottom: 8px; font-size: 15px;
  line-height: 1.6; color: var(--text-main); max-height: 30vh; overflow-y: auto;
}
#markBackdrop { z-index: 100; }
/* body 整頁禁反白（防誤觸）→ 課文、題目、解析開放反白才能畫線 */
.lesson-box, .quiz-question, .explanation-box, .card-title, textarea {
  user-select: text; -webkit-user-select: text;
}
/* 課的完成狀態（9/25） */
.status-badge { display: inline-block; font-size: 13px; padding: 4px 10px; border-radius: 999px; margin: -4px 0 12px; }
.status-badge.full { background: var(--correct-bg); color: var(--correct-text); border: 1px solid var(--correct-border); }
.status-badge.old, .status-badge.long { background: var(--tag-bg); color: var(--tag-text); border: 1px solid var(--accent-gold); }