@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700&family=Noto+Sans+TC:wght@300;400;500;700&display=swap');

:root {
  /* POBI STUDIO Official Brand Colors (Brand Master Guideline v1.3) */
  --pobi-blue: #001F65;
  --pobi-green: #197A27;
  --pobi-background: #FFFFFF;
  --pobi-surface: #FAF7F0;
  --pobi-dark-background: #0B1220;

  /* Light Theme (Default: 溫潤米黃書頁紙張 + 實體手作筆記本質感) */
  color-scheme: light;
  --bg-primary: #F4EFEB;           /* 典雅書桌/桌面底色 */
  --bg-secondary: #FAF7F0;         /* 溫潤米白筆記卡片底色 */
  --notebook-paper: #FAF6ED;       /* 經典米黃書頁色 (Warm Cream / Ivory) */
  --notebook-desk: #ECE6DE;        /* 木質/皮革書桌質感 */
  --notebook-line: rgba(0, 31, 101, 0.06); /* 筆記紙橫線淡印 */
  --notebook-margin: rgba(25, 122, 39, 0.28); /* 活頁裝訂與邊界紅綠墨水線 */
  --notebook-stitch: rgba(0, 31, 101, 0.14); /* 車縫裝訂線 */

  --glass-bg: #FAF7F0;
  --glass-border: #D8D0C5;         /* 實體裝訂紙張邊緣邊框 */
  --glass-highlight: #F0EAE1;
  
  --text-primary: #001F65;         /* POBI Blue 深海軍藍墨水 (高對比清楚清晰) */
  --text-secondary: #1E293B;       /* 深石板墨水色 */
  --text-muted: #526178;           /* 輔助墨水色 (非過淺灰，維持高易讀性) */
  
  --accent-primary: #001F65;
  --accent-secondary: #197A27;
  --accent-gradient: linear-gradient(100deg, #001F65, #197A27);
  --accent-gradient-hover: linear-gradient(100deg, #00174A, #146320);
  --title-gradient: linear-gradient(100deg, #001F65 0%, #156621 100%);
  
  --success: #197A27;
  --success-glow: rgba(25, 122, 39, 0.16);
  --danger: #B91C1C;
  --danger-glow: rgba(185, 28, 28, 0.14);
  --warning: #92400E;             /* 溫暖赭黃/焦糖，高對比易讀 (WCAG AAA) */
  --warning-bg: #FEF3C7;
  --warning-border: #D97706;
  --warning-text: #78350F;
  --warning-glow: rgba(180, 83, 9, 0.14);
  
  --shadow-sm: 0 1px 3px rgba(0, 31, 101, 0.05);
  --shadow-md: 0 4px 14px rgba(0, 31, 101, 0.08), 0 1px 3px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 25px rgba(0, 31, 101, 0.1), 0 2px 6px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 35px rgba(0, 31, 101, 0.14), 0 5px 12px rgba(0, 0, 0, 0.06);
  
  --washi-tape-green: rgba(25, 122, 39, 0.32);
  --washi-tape-blue: rgba(0, 31, 101, 0.25);
  --washi-tape-amber: rgba(180, 83, 9, 0.28);

  --font-sans: 'Outfit', 'Noto Sans TC', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-xl: 20px;
}

[data-theme="dark"] {
  color-scheme: dark;
  /* Dark Theme (深色工程風 + 深色皮革活頁手帳) */
  --bg-primary: #0B1220;           /* POBI Dark 主背景 */
  --bg-secondary: #121D2F;         /* 深海軍藍活頁夾卡片底色 */
  --notebook-paper: #121E31;       /* 深色紙張底色 */
  --notebook-desk: #080D17;        /* 深色桌面 */
  --notebook-line: rgba(255, 255, 255, 0.05);
  --notebook-margin: rgba(74, 222, 128, 0.3);
  --notebook-stitch: rgba(255, 255, 255, 0.12);

  --glass-bg: rgba(18, 29, 47, 0.95);
  --glass-border: rgba(255, 255, 255, 0.18);
  --glass-highlight: rgba(0, 31, 101, 0.5);
  
  --text-primary: #FFFFFF;         /* 純白高對比 */
  --text-secondary: #E2E8F0;       /* 白銀灰 (高可讀性，絕非深色字) */
  --text-muted: #94A3B8;           /* 淺灰字體 */
  
  --accent-primary: #22C55E;       /* 明亮科技綠 */
  --accent-secondary: #38BDF8;     /* 亮青藍 */
  --accent-gradient: linear-gradient(100deg, #197A27, #22C55E);
  --accent-gradient-hover: linear-gradient(100deg, #146320, #16A34A);
  --title-gradient: linear-gradient(100deg, #FFFFFF 15%, #4ADE80 85%); /* 深色模式高對比標題白綠漸層 */
  
  --success: #22C55E;
  --success-glow: rgba(34, 197, 94, 0.25);
  --danger: #EF4444;
  --danger-glow: rgba(239, 68, 68, 0.25);
  --warning: #FBBF24;
  --warning-bg: rgba(245, 158, 11, 0.16);
  --warning-border: rgba(251, 191, 36, 0.5);
  --warning-text: #FDE68A;
  --warning-glow: rgba(251, 191, 36, 0.25);

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.55);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.65);
  --shadow-xl: 0 20px 35px rgba(0, 0, 0, 0.75);

  --washi-tape-green: rgba(34, 197, 94, 0.4);
  --washi-tape-blue: rgba(56, 189, 248, 0.4);
  --washi-tape-amber: rgba(251, 191, 36, 0.4);
}

/* Global Reset & Base Styling */

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

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  min-height: 100vh;
  line-height: 1.5;
  overflow-x: hidden;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Ambient Desk Atmosphere (溫暖木質/皮革書桌氛圍，告別冰冷AI光斑) */

.bg-ambient-lights {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
  pointer-events: none;
  overflow: hidden;
  background: 
    radial-gradient(ellipse at 50% 0%, rgba(255, 255, 255, 0.7) 0%, transparent 65%),
    linear-gradient(180deg, rgba(0, 31, 101, 0.02) 0%, rgba(25, 122, 39, 0.02) 100%);
}

[data-theme="dark"] .bg-ambient-lights {
  background: 
    radial-gradient(ellipse at 50% 0%, rgba(0, 31, 101, 0.3) 0%, transparent 75%),
    #0B1220;
}

.pobi-gradient {
  background: linear-gradient(100deg, var(--pobi-blue), var(--pobi-green));
}

/* =======================================================
   Physical Notebook & Hardcover Skeuomorphic Styles
   ======================================================= */

/* Physical Notebook Outer Frame & Binder Spine */

.notebook-desk {
  background-color: var(--notebook-desk);
}

.notebook-page {
  background-color: var(--notebook-paper);
  background-image: 
    linear-gradient(to right, var(--notebook-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--notebook-line) 1px, transparent 1px);
  background-size: 22px 22px;
  border: 1px solid var(--glass-border);
  box-shadow: 
    0 1px 3px rgba(0, 0, 0, 0.05),
    0 10px 28px rgba(0, 31, 101, 0.08),
    -3px 0 0 -1px var(--notebook-paper),
    -4px 0 0 0 var(--glass-border),
    -7px 0 0 -1px var(--notebook-paper),
    -8px 0 0 0 var(--glass-border);
  position: relative;
}

/* Hardcover Book Cover (實體精裝書本封面 - 用於登入頁面) */

.hardcover-book-wrapper {
  position: relative;
  width: 100%;
  max-width: 480px;
  perspective: 1000px;
}

.hardcover-book {
  position: relative;
  background: linear-gradient(145deg, #00174B 0%, #001F65 50%, #062B75 100%);
  border-radius: 6px 18px 18px 6px;
  padding: 34px 28px 34px 42px;
  box-shadow: 
    -15px 0 28px rgba(0, 0, 0, 0.45),      /* 書脊左側立體厚度陰影 */
    0 18px 45px rgba(0, 31, 101, 0.28),     /* 書底投影 */
    inset 0 0 0 1px rgba(255, 255, 255, 0.12),
    inset -3px 0 8px rgba(0, 0, 0, 0.35);    /* 書槽開闔壓痕 */
  border-left: 20px solid #001338;          /* 精裝厚實書脊 */
  overflow: hidden;
}

/* 書脊上的燙金/車縫凹槽線 */

.hardcover-book::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 4px;
  background: linear-gradient(to bottom, 
    transparent 0%, 
    rgba(255, 215, 0, 0.35) 20%, 
    rgba(255, 215, 0, 0.35) 80%, 
    transparent 100%
  );
  box-shadow: 1px 0 3px rgba(0, 0, 0, 0.6);
  z-index: 5;
}

/* 封面車縫線外框 */

.cover-stitched-frame {
  position: absolute;
  inset: 10px 10px 10px 18px;
  border: 1px dashed rgba(255, 255, 255, 0.25);
  border-radius: 4px 12px 12px 4px;
  pointer-events: none;
  z-index: 2;
}

/* 書角金色包角 (Brass Book Corners) */

.book-corner-brass {
  position: absolute;
  width: 28px;
  height: 28px;
  border: 2px solid #D4AF37;
  pointer-events: none;
  z-index: 10;
}

.book-corner-tr {
  top: 4px;
  right: 4px;
  border-left: none;
  border-bottom: none;
  border-radius: 0 14px 0 0;
  background: radial-gradient(circle at top right, rgba(212, 175, 55, 0.45) 0%, transparent 70%);
}

.book-corner-br {
  bottom: 4px;
  right: 4px;
  border-left: none;
  border-top: none;
  border-radius: 0 0 14px 0;
  background: radial-gradient(circle at bottom right, rgba(212, 175, 55, 0.45) 0%, transparent 70%);
}

/* 垂掛緞面書籤絲帶 (Bookmark Ribbon) */

.book-ribbon-tag {
  position: absolute;
  top: -2px;
  right: 36px;
  width: 22px;
  height: 64px;
  background: linear-gradient(180deg, #197A27 0%, #11591C 100%);
  clip-path: polygon(0 0, 100% 0, 100% 100%, 50% 82%, 0 100%);
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.35);
  z-index: 15;
  pointer-events: none;
}

/* 封面上的米黃藏書票/扉頁 (Bookplate Insertion Page) */

.bookplate-insert {
  position: relative;
  background: #FAF6ED;                      /* 溫潤米黃紙質 */
  background-image: radial-gradient(rgba(0, 31, 101, 0.05) 1px, transparent 1px);
  background-size: 16px 16px;
  border: 1px solid #D4C9BA;
  border-radius: 8px;
  padding: 28px 24px 22px 24px;
  box-shadow: 
    0 2px 8px rgba(0, 0, 0, 0.18),
    0 8px 20px rgba(0, 0, 0, 0.12);
  z-index: 5;
}

/* Physical Notebook Spiral Binder / Spine indicator */

.notebook-binder-edge {
  position: relative;
}

.notebook-binder-edge::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 16px;
  background: repeating-linear-gradient(
    to bottom,
    transparent 0px,
    transparent 28px,
    rgba(0, 31, 101, 0.12) 28px,
    rgba(0, 31, 101, 0.2) 32px,
    transparent 36px
  );
  border-right: 1px dashed var(--glass-border);
  pointer-events: none;
  z-index: 2;
}

/* Notebook Header with Bookmark Ribbon */

.notebook-header-ribbon {
  position: relative;
}

.notebook-header-ribbon::after {
  content: "";
  position: absolute;
  top: 0;
  right: 28px;
  width: 14px;
  height: 38px;
  background: linear-gradient(180deg, var(--accent-secondary), #0e5218);
  clip-path: polygon(0 0, 100% 0, 100% 100%, 50% 82%, 0 100%);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
  z-index: 10;
}

/* Scrapbook Washi Tape Strips (和紙膠帶剪貼效果) */

.washi-tape-strip {
  position: relative;
}

.washi-tape-strip::before {
  content: "";
  position: absolute;
  top: -10px;
  left: 50%;
  transform: translateX(-50%) rotate(-0.8deg);
  width: 110px;
  height: 22px;
  background: var(--washi-tape-green);
  border-left: 3px dashed rgba(255, 255, 255, 0.7);
  border-right: 3px dashed rgba(255, 255, 255, 0.7);
  box-shadow: 0 1px 4px rgba(0, 31, 101, 0.12);
  z-index: 8;
  pointer-events: none;
}

.washi-tape-blue::before {
  background: var(--washi-tape-blue);
  transform: translateX(-50%) rotate(0.6deg);
}

.washi-tape-amber::before {
  background: var(--washi-tape-amber);
  transform: translateX(-50%) rotate(-1.2deg);
}

/* Clipped Scrapbook Flashcard (剪貼卡片質感) */

.scrapbook-card {
  background: var(--bg-secondary);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  box-shadow: 
    0 2px 6px rgba(0, 31, 101, 0.05),
    0 8px 20px rgba(0, 31, 101, 0.08);
  position: relative;
  transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.25s ease;
}

.scrapbook-card:hover {
  transform: translateY(-2px);
  box-shadow: 
    0 4px 10px rgba(0, 31, 101, 0.08),
    0 14px 28px rgba(0, 31, 101, 0.12);
}

/* Sticky Memo Note (剪貼便利貼新增框) */

.memo-note {
  background: var(--notebook-paper);
  border: 1.5px dashed var(--accent-secondary);
  border-radius: 10px;
  box-shadow: 2px 4px 14px rgba(0, 31, 101, 0.08);
  position: relative;
}

/* Notebook Index Tab (側邊活頁索引貼) */

.notebook-index-tab {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  font-size: 0.84rem;
  font-weight: 600;
  border-radius: 8px 8px 0 0;
  border-top: 2px solid var(--accent-secondary);
  background: var(--glass-bg);
  box-shadow: 0 -2px 6px rgba(0, 31, 101, 0.05);
  cursor: pointer;
  transition: all 0.2s ease;
}

.notebook-index-tab.active {
  background: var(--notebook-paper);
  border-top: 3px solid var(--accent-primary);
  color: var(--accent-primary);
  box-shadow: 0 -4px 10px rgba(0, 31, 101, 0.09);
}

/* Glassmorphism Styles */

.glass {
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  box-shadow: var(--shadow-md);
  border-radius: var(--radius-lg);
}

.glass-card {
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-md);
  transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), box-shadow 0.3s ease, border-color 0.3s ease;
}

.glass-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(0, 31, 101, 0.25);
}

/* Typography & Headers */

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  letter-spacing: -0.02em;
}

.title-gradient {
  background: var(--title-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  color: var(--text-primary);
}

.navbar-title {
  font-weight: 700;
  letter-spacing: -0.01em;
}

[data-theme="light"] .navbar-title {
  color: #001F65;
  background: linear-gradient(100deg, #001F65 0%, #156621 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

[data-theme="dark"] .navbar-title {
  color: #FFFFFF;
  background: linear-gradient(100deg, #FFFFFF 15%, #4ADE80 85%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Sidebar Specific High-Contrast Elements */

.sidebar-section2-title {
  font-size: 0.82rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: color 0.2s ease;
}

[data-theme="light"] .sidebar-section2-title {
  color: #92400E; /* 深琥珀棕色，淺色底超清晰 */
}

[data-theme="dark"] .sidebar-section2-title {
  color: #FCD34D; /* 明亮金色，深色底清晰可辨 */
}

/* Sidebar Add Subject Button */

.btn-sidebar-add {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  padding: 3px 8px;
  font-size: 0.74rem;
  font-weight: 700;
  border-radius: 6px;
  transition: all 0.2s ease;
}

[data-theme="light"] .btn-sidebar-add {
  background: #E8F5E9;
  border: 1px solid #A5D6A7;
  color: #14532D;
}

[data-theme="light"] .btn-sidebar-add:hover {
  background: #C8E6C9;
}

[data-theme="dark"] .btn-sidebar-add {
  background: rgba(74, 222, 128, 0.18);
  border: 1px solid rgba(74, 222, 128, 0.4);
  color: #4ADE80;
}

[data-theme="dark"] .btn-sidebar-add:hover {
  background: rgba(74, 222, 128, 0.28);
}

/* Scope Badges with High Contrast */

.scope-badge-global {
  font-size: 0.68rem;
  padding: 1px 6px;
  border-radius: 4px;
  font-weight: 700;
  flex-shrink: 0;
}

[data-theme="light"] .scope-badge-global {
  background: #E8F5E9;
  color: #14532D;
  border: 1px solid #C8E6C9;
}

[data-theme="dark"] .scope-badge-global {
  background: rgba(34, 197, 94, 0.22);
  color: #4ADE80;
  border: 1px solid rgba(74, 222, 128, 0.35);
}

.scope-badge-subject {
  font-size: 0.68rem;
  padding: 1px 6px;
  border-radius: 4px;
  font-weight: 700;
  flex-shrink: 0;
}

[data-theme="light"] .scope-badge-subject {
  background: #EDE9FE;
  color: #4C1D95;
  border: 1px solid #DDD6FE;
}

[data-theme="dark"] .scope-badge-subject {
  background: rgba(165, 180, 252, 0.22);
  color: #C7D2FE;
  border: 1px solid rgba(165, 180, 252, 0.35);
}

.scope-badge-chapter {
  font-size: 0.68rem;
  padding: 1px 6px;
  border-radius: 4px;
  font-weight: 700;
  flex-shrink: 0;
}

[data-theme="light"] .scope-badge-chapter {
  background: #FEF3C7;
  color: #92400E;
  border: 1px solid #FDE68A;
}

[data-theme="dark"] .scope-badge-chapter {
  background: rgba(251, 191, 36, 0.22);
  color: #FDE047;
  border: 1px solid rgba(251, 191, 36, 0.35);
}

/* Buttons */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-sans);
  font-weight: 500;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  text-decoration: none;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(0, 31, 101, 0.22);
}

.btn-primary:hover {
  opacity: 0.95;
  transform: translateY(-1px);
  box-shadow: 0 6px 18px rgba(0, 31, 101, 0.3);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background: var(--glass-highlight);
  border-color: var(--text-secondary);
}

.btn-danger {
  background: var(--danger);
  color: #ffffff;
  box-shadow: 0 4px 12px var(--danger-glow);
}

.btn-danger:hover {
  opacity: 0.95;
  transform: translateY(-1px);
}

.btn-text {
  background: transparent;
  color: var(--text-secondary);
  padding: 6px 12px;
}

.btn-text:hover {
  color: var(--text-primary);
  background: var(--glass-bg);
}

/* Inputs & Form Controls */

.form-group {
  margin-bottom: 20px;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.input {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg-secondary);
  border: 1.5px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 1rem;
  outline: none;
  transition: all 0.2s ease;
}

.input:focus {
  border-color: var(--accent-secondary);
  box-shadow: 0 0 0 3px rgba(25, 122, 39, 0.18);
}

.input::placeholder {
  color: var(--text-muted);
}

select.input {
  background-color: var(--bg-secondary) !important;
  color: var(--text-primary) !important;
  border-color: var(--glass-border) !important;
  font-weight: 500;
}

select.input option,
select.input optgroup,
select option,
select optgroup {
  background-color: var(--bg-secondary) !important;
  color: var(--text-primary) !important;
  font-weight: 500;
}

[data-theme="light"] select.input {
  background-color: #ffffff !important;
  color: #001F65 !important;
  border-color: rgba(0, 31, 101, 0.18) !important;
  font-weight: 600;
}

[data-theme="light"] select.input option,
[data-theme="light"] select.input optgroup,
[data-theme="light"] select option,
[data-theme="light"] select optgroup {
  background-color: #ffffff !important;
  color: #001F65 !important;
  font-weight: 600;
}

[data-theme="dark"] select.input {
  background-color: #101B2E !important;
  color: #ffffff !important;
  border-color: rgba(255, 255, 255, 0.2) !important;
  font-weight: 500;
}

[data-theme="dark"] select.input option,
[data-theme="dark"] select.input optgroup,
[data-theme="dark"] select option,
[data-theme="dark"] select optgroup {
  background-color: #101B2E !important;
  color: #ffffff !important;
  font-weight: 500;
}

[data-theme="light"] select option,
[data-theme="light"] select optgroup {
  background-color: #ffffff;
  color: #0f172a;
  font-weight: 500;
}

.input-checkbox {
  width: 18px;
  height: 18px;
  accent-color: var(--accent-primary);
  cursor: pointer;
}

/* Layout Utilities */

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.grid {
  display: grid;
  gap: 24px;
}

.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }

.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }

.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 900px) {
  .grid-cols-3, .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 600px) {
  .grid-cols-2, .grid-cols-3, .grid-cols-4 { grid-template-columns: 1fr; }
}

/* Animations */

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
  animation: fadeIn 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Custom Collapsible details/summary */

.collapsible-container {
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: rgba(0, 0, 0, 0.1);
  margin-top: 12px;
}

.collapsible-trigger {
  padding: 12px 16px;
  background: var(--glass-bg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  cursor: pointer;
  user-select: none;
  font-weight: 500;
  transition: background 0.2s ease;
}

.collapsible-trigger:hover {
  background: var(--glass-highlight);
}

.collapsible-content {
  padding: 16px;
  border-top: 1px solid var(--glass-border);
  animation: fadeIn 0.3s ease;
}

/* Print CSS Stylesheet */

@media print {
  body {
    background: #ffffff !important;
    color: #000000 !important;
    font-size: 12pt;
    font-family: 'Noto Sans TC', sans-serif !important;
  }
  
  .bg-ambient-lights,
  header,
  nav,
  .no-print,
  .btn,
  .theme-toggle,
  .collapsible-trigger svg,
  .sidebar,
  .filters-container {
    display: none !important;
  }

  .container {
    max-width: 100% !important;
    width: 100% !important;
    margin: 0 !important;
    padding: 0 !important;
  }

  .print-page {
    page-break-after: always;
  }

  /* Force display of answers in Complete/解析 mode during print */
  .print-solution-mode .collapsible-content {
    display: block !important;
    border-top: 1px dashed #cccccc !important;
    margin-top: 10px !important;
    padding-top: 10px !important;
  }

  /* Force hide answers in Practice/練習 mode during print */
  .print-practice-mode .collapsible-container,
  .print-practice-mode .collapsible-content,
  .print-practice-mode .answer-section {
    display: none !important;
  }

  .mistake-card-print {
    border: 1px solid #000000 !important;
    border-radius: 4px !important;
    padding: 15px !important;
    margin-bottom: 25px !important;
    page-break-inside: avoid !important;
    background: transparent !important;
    box-shadow: none !important;
  }

  .mistake-card-print h3 {
    border-bottom: 1px solid #000000 !important;
    padding-bottom: 5px !important;
    margin-bottom: 10px !important;
  }

  .print-grid {
    display: grid !important;
    grid-template-columns: 1fr !important;
    gap: 15px !important;
  }

  img {
    max-width: 80% !important;
    max-height: 4in !important;
    display: block !important;
    margin: 10px 0 !important;
    page-break-inside: avoid !important;
  }
}

/* ========================================
   Modal Overlay & Content
   ======================================== */

.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
}

.modal-content {
  position: relative;
  max-height: 90vh;
  overflow-y: auto;
}

/* ========================================
   Sidebar Transitions
   ======================================== */

.sidebar {
  transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.sidebar-collapsed {
  width: 48px !important;
}

.sidebar-expanded {
  width: 300px;
}

/* ========================================
   Spin Animation (for loaders)
   ======================================== */

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

.animate-spin {
  animation: spin 1s linear infinite;
}

/* ========================================
   Responsive Layout
   ======================================== */

/* Mobile: <768px */

@media (max-width: 767px) {
  /* Navbar responsive */
  .top-navbar {
    height: auto !important;
    min-height: 56px;
    padding: 8px 12px !important;
    flex-wrap: wrap;
    gap: 8px;
  }

  .navbar-brand {
    flex: 1;
    min-width: 0;
  }

  .navbar-title {
    font-size: 1rem !important;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  .navbar-actions {
    flex-wrap: wrap;
    gap: 6px !important;
    justify-content: flex-end;
  }

  .navbar-btn-text {
    display: none;
  }

  .navbar-user-info {
    display: none;
  }

  /* Sidebar defaults collapsed on mobile */
  .sidebar-expanded {
    position: fixed;
    left: 0;
    top: 56px;
    z-index: 40;
    width: 280px !important;
    height: calc(100vh - 56px) !important;
    box-shadow: 4px 0 24px rgba(0, 0, 0, 0.3);
    background: var(--bg-secondary) !important;
  }

  .sidebar-collapsed {
    width: 40px !important;
  }

  /* Main content full width */
  .main-layout {
    flex-direction: row;
  }

  /* Glass card adjustments */
  .glass-card {
    padding: 16px;
  }

  .glass {
    padding: 16px;
  }

  /* Table responsive */
  .glass-card table {
    font-size: 0.8rem;
  }

  .glass-card th, .glass-card td {
    padding: 8px 10px !important;
  }
}

/* Tablet: 768px - 1024px */

@media (min-width: 768px) and (max-width: 1024px) {
  .sidebar-expanded {
    width: 240px !important;
  }

  .navbar-btn-text {
    display: none;
  }

  .top-navbar {
    padding: 0 16px !important;
  }

  .glass-card {
    padding: 20px;
  }
}

/* Desktop: >1024px */

@media (min-width: 1025px) {
  .sidebar-expanded {
    width: 300px;
  }
}

/* High Contrast Warning Alert Banner & Tags (WCAG AAA Compliant in Light & Dark Modes) */

.warning-alert-banner {
  padding: 14px 18px;
  border-radius: var(--radius-md);
  background: var(--warning-bg);
  border: 1.5px solid var(--warning-border);
  display: flex;
  align-items: flex-start;
  gap: 12px;
  color: var(--warning-text);
  box-shadow: var(--shadow-sm);
}

.warning-alert-banner svg {
  color: var(--warning-border);
  flex-shrink: 0;
  margin-top: 2px;
}

.warning-alert-banner strong {
  color: var(--warning-text);
  font-weight: 700;
}

.badge-warning-contrast {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 4px;
  background: var(--warning-bg);
  border: 1px solid var(--warning-border);
  color: var(--warning-text);
  display: inline-block;
}

.badge-recommended-tag {
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 7px;
  border-radius: 4px;
  background: #D97706;
  color: #FFFFFF;
  display: inline-block;
}

[data-theme="dark"] .badge-recommended-tag {
  background: #FBBF24;
  color: #0F172A;
}