/* ==========================================================================
   Design tokens / 設計變數（含暗色模式）
   ========================================================================== */
:root {
  /* 品牌色 */
  --brand: #0A74FF;
  --brand-hover: #0861E0;

  /* 基礎色階 */
  --bg: #ffffff;
  --surface: #ffffff;            /* 卡片/區塊底 */
  --elevated: #ffffff;           /* 浮層/強調底 */
  --section: #f8fafc;            /* 區段背景 */
  --border: #e5e7eb;             /* 邊框 */
  --text: #1f2937;               /* 主文字 */
  --text-light: #4b5563;         /* 次文字 */
  --muted: #6b7280;              /* 淡文字 */

  /* 半徑 / 陰影 */
  --radius: 16px;
  --radius-sm: 8px;
  --radius-full: 999px;
  --shadow: 0 6px 16px rgba(0,0,0,.06);
  --shadow-lg: 0 14px 34px rgba(0,0,0,.10);

  /* 間距（改用 rem 更一致） */
  --spacing-xs: 0.5rem;   /* 8px */
  --spacing-sm: 0.75rem;  /* 12px */
  --spacing-md: 1rem;     /* 16px */
  --spacing-lg: 1.25rem;  /* 20px */
  --spacing-xl: 1.5rem;   /* 24px */
  --spacing-2xl: 2rem;    /* 32px */
  --spacing-3xl: 3rem;    /* 48px */
  --spacing-4xl: 5rem;    /* 80px */

  /* 字級（以 clamp 提升比例感） */
  --text-xs: clamp(0.72rem, 0.68rem + 0.3vw, 0.75rem);
  --text-sm: clamp(0.82rem, 0.78rem + 0.3vw, 0.875rem);
  --text-base: clamp(0.9rem, 0.86rem + 0.35vw, 0.95rem);
  --text-md: clamp(1rem, 0.96rem + 0.4vw, 1.05rem);
  --text-lg: clamp(1.05rem, 1rem + 0.5vw, 1.125rem);
  --text-xl: clamp(1.2rem, 1.12rem + 0.6vw, 1.25rem);
  --text-2xl: clamp(1.35rem, 1.22rem + 0.8vw, 1.5rem);
  --text-3xl: clamp(1.6rem, 1.4rem + 1vw, 1.75rem);
  --text-4xl: clamp(2rem, 1.7rem + 1.6vw, 2.25rem);
  --text-5xl: clamp(2.6rem, 2.1rem + 2.4vw, 3rem);

  /* 動畫 */
  --transition: 160ms ease;

  /* 版型 */
  --navbar-height: 56px;
  --container-width: 1200px;

  /* 標籤 */
  --tag-problem-bg: #fee2e2;
  --tag-problem-color: #dc2626;
  --tag-solution-bg: #dcfce7;
  --tag-solution-color: #16a34a;

  /* 輔助 */
  --focus-ring: 0 0 0 3px rgba(10,116,255,.15);
  --link: #0a66ff;
}

/* Dark mode tokens */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1020;
    --surface: #12182a;
    --elevated: #161e33;
    --section: #0f1426;
    --border: #1f2a44;
    --text: #e6eaf2;
    --text-light: #b9c0cf;
    --muted: #93a0b7;
    --shadow: 0 6px 16px rgba(0,0,0,.35);
    --shadow-lg: 0 20px 44px rgba(0,0,0,.45);
    --link: #6aa3ff;
  }
}

/* ==========================================================================
   Reset / 基礎
   ========================================================================== */
*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-padding-top: calc(var(--navbar-height) + 24px); }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Inter, "Noto Sans TC", "Helvetica Neue", Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a[href^="#"] { scroll-behavior: smooth; }

a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

::selection { background: rgba(10,116,255,.18); color: inherit; }

:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 2px;
  box-shadow: var(--focus-ring);
}

/* 容器 */
.container {
  max-width: var(--container-width);
  margin-inline: auto;
  padding-inline: var(--spacing-lg);
}

/* ==========================================================================
   Navbar
   ========================================================================== */
.navbar {
  position: fixed;
  inset-inline: 0;
  inset-block-start: 0;
  background: color-mix(in oklab, var(--surface) 95%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  min-height: var(--navbar-height);
}

.nav-container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: var(--spacing-sm) var(--spacing-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: var(--text-2xl);
}

.nav-logo {
  inline-size: 32px;
  block-size: 32px;
  border-radius: var(--radius-sm);
}

/* 統一按鈕樣式（nav-cta 沿用） */
.btn, .nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5em;
  background: var(--brand);
  color: #fff;
  padding: var(--spacing-sm) 1.6rem;
  border-radius: var(--radius-full);
  font-size: var(--text-lg);
  font-weight: 600;
  border: 1px solid transparent;
  transition: transform var(--transition), background var(--transition), box-shadow var(--transition);
  will-change: transform;
  text-decoration: none;
}
.btn:hover, .nav-cta:hover { background: var(--brand-hover); transform: translateY(-1px); }
.btn:active, .nav-cta:active { transform: translateY(0); }

/* ==========================================================================
   Hero / 視訊區
   ========================================================================== */
.video-hero {
  margin-top: var(--navbar-height);
  min-height: clamp(52vh, 56vh, 60vh);
  background: var(--section);
  display: flex;
  align-items: flex-start;
  padding-block: 5px 15px;
  text-align: center;
}

.video-hero .container {
  inline-size: 100%;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  align-items: center;
  gap: var(--spacing-xs);
}

.video-hero .hero-title {
  font-size: var(--text-5xl);
  font-weight: 550;
  color: var(--text);
  margin-bottom: 2px;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.video-hero .hero-title::after {
  content: '|';
  font-weight: 400;
  color: var(--brand);
  animation: blink 1s steps(2, end) infinite;
}

.video-hero .hero-title.typing-complete::after { display: none; }

@keyframes blink {
  0%, 50% { opacity: 1; }
  50.01%, 100% { opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .video-hero .hero-title::after { animation: none; }
}

.video-hero .hero-subtitle {
  font-family: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, "Noto Sans TC", Arial, sans-serif;
  font-size: var(--text-2xl);
  font-weight: 400;
  color: var(--text-light);
  margin: 0;
  letter-spacing: 0.02em;
}

/* ==========================================================================
   通用區塊
   ========================================================================== */
.section { padding-block: var(--spacing-4xl); }
.section.bg { background: var(--section); }

.section-title {
  font-size: var(--text-4xl);
  font-weight: 800;
  text-align: center;
  margin-bottom: var(--spacing-3xl);
  letter-spacing: -0.01em;
}

/* 通用卡片（抽出共用，原類名沿用） */
.card,
.feature-card,
.use-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}

.card:hover,
.feature-card:hover,
.use-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* ==========================================================================
   功能特色
   ========================================================================== */
.features {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-xl);
  max-width: var(--container-width);
  margin: 0 auto;
}

.feature-card {
  padding: var(--spacing-2xl) var(--spacing-lg);
  text-align: center;
  min-height: 220px;
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
}

.feature-icon {
  font-size: var(--text-4xl);
  margin-bottom: var(--spacing-md);
}

.feature-card h3 {
  font-size: var(--text-xl);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
}

.feature-card p {
  color: var(--text-light);
  font-size: var(--text-base);
  line-height: 1.6;
}

/* ==========================================================================
   統計數據
   ========================================================================== */
.stats-section { background: var(--section); }

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--spacing-2xl);
  max-width: 860px;
  margin: 0 auto;
}

.stat-card { text-align: center; padding: var(--spacing-2xl) var(--spacing-lg); }

.stat-number {
  font-size: clamp(2.4rem, 2.2rem + 2vw, 3.2rem);
  font-weight: 800;
  color: var(--brand);
  line-height: 1;
  margin-bottom: var(--spacing-sm);
  font-family: 'Poppins', system-ui, -apple-system, Segoe UI, Roboto, Inter, "Noto Sans TC", Arial, sans-serif;
  letter-spacing: -0.02em;
}

.stat-label {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text);
  margin: 0;
}

/* ==========================================================================
   問題 / 解法
   ========================================================================== */
.problem-solution {
  text-align: center;
  padding-block: var(--spacing-4xl);
  background: var(--section);
}

.problem-solution-card {
  max-width: 900px;
  margin-inline: auto;
  padding: var(--spacing-3xl) var(--spacing-lg);
}

.problem-text {
  margin-bottom: var(--spacing-2xl);
}

.problem-title {
  font-size: var(--text-4xl);
  font-weight: 800;
  color: var(--text);
  margin-bottom: var(--spacing-lg);
  line-height: 1.25;
}

.problem-subtitle {
  font-size: var(--text-xl);
  color: var(--text-light);
  margin: 0 0 var(--spacing-2xl);
  line-height: 1.6;
}

.solution-text {
  margin: 0;
}

.solution-highlight {
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--brand);
  margin: 0;
  line-height: 1.4;
}

/* ==========================================================================
   使用情境卡片
   ========================================================================== */
.use-cases {
  display: flex;
  flex-direction: column;
  gap: 40px;
  max-width: 1400px;
  margin: 0 auto;
}

.use-card { overflow: hidden; }

.use-card.horizontal {
  display: flex;
  align-items: center;
  min-height: 360px;
  position: relative;
}

.use-card.horizontal img {
  inline-size: clamp(320px, 42vw, 520px);
  block-size: clamp(220px, 30vw, 350px);
  object-fit: cover;
  flex-shrink: 0;
}

.use-card.horizontal .use-content {
  padding: clamp(28px, 4vw, 60px);
  flex: 1;
}

.use-card.horizontal.reverse { flex-direction: row-reverse; }

.use-content h3 {
  font-size: var(--text-2xl);
  font-weight: 700;
  margin-bottom: var(--spacing-md);
}

.use-problem,
.use-solution {
  font-size: var(--text-lg);
  line-height: 1.75;
  margin-bottom: var(--spacing-sm);
  font-weight: 400;
  color: var(--text-light);
}

.use-solution {
  margin-bottom: var(--spacing-md);
  font-weight: 600;
  color: var(--text);
}

.use-benefit {
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--brand);
  margin: var(--spacing-md) 0 var(--spacing-sm);
}

.use-target {
  font-size: var(--text-md);
  color: var(--muted);
  margin-top: var(--spacing-xs);
}

/* ==========================================================================
   影片容器
   ========================================================================== */
.video-container {
  position: relative;
  inline-size: 100%;
  max-width: 860px;
  margin: 0 auto;
  padding-bottom: 56.25%;
  block-size: 0;
  overflow: hidden;
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  transform: translateZ(0);
  backface-visibility: hidden;
  isolation: isolate;
  cursor: pointer;
  border: 1px solid var(--border);
}

.video-container iframe {
  position: absolute;
  inset: 0;
  inline-size: 100%;
  block-size: 100%;
  border-radius: var(--radius);
  background: var(--elevated);
  border: none;
}

/* ==========================================================================
   標籤
   ========================================================================== */
.tag {
  display: inline-block;
  padding: 2px var(--spacing-xs);
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  margin-right: var(--spacing-xs);
  border: 1px solid transparent;
}

.use-problem .tag {
  background: var(--tag-problem-bg);
  color: var(--tag-problem-color);
  border-color: color-mix(in oklab, var(--tag-problem-bg), #000 6%);
}

.use-solution .tag {
  background: var(--tag-solution-bg);
  color: var(--tag-solution-color);
  border-color: color-mix(in oklab, var(--tag-solution-bg), #000 6%);
}

/* ==========================================================================
   使用步驟
   ========================================================================== */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--spacing-2xl);
  max-width: 900px;
  margin: 0 auto;
  position: relative;
}

.steps::before {
  content: '';
  position: absolute;
  top: var(--spacing-2xl);
  left: calc(16.66% - var(--spacing-lg));
  right: calc(16.66% - var(--spacing-lg));
  height: 2px;
  background: linear-gradient(90deg, var(--border) 50%, transparent 50%);
  background-size: var(--spacing-lg) 2px;
  z-index: 0;
}

.step { text-align: center; position: relative; }

.step-number {
  inline-size: 64px;
  block-size: 64px;
  background: var(--brand);
  color: white;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-size: var(--text-2xl);
  font-weight: 800;
  margin: 0 auto var(--spacing-xl);
  position: relative;
  z-index: 1;
  box-shadow: 0 4px 10px rgba(10,116,255,.25);
}

.step-content h3 {
  font-size: var(--text-lg);
  font-weight: 700;
  margin-bottom: var(--spacing-xs);
}

.step-content p {
  font-size: var(--text-base);
  color: var(--text-light);
}

/* ==========================================================================
   下載按鈕
   ========================================================================== */
.download-apps { text-align: center; padding-block: 40px; }

.download-buttons {
  display: flex;
  gap: var(--spacing-xl);
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  margin-top: var(--spacing-2xl);
}

.download-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-sm);
  background: var(--brand);
  color: #fff;
  padding: var(--spacing-lg) var(--spacing-2xl);
  border-radius: var(--radius);
  font-size: var(--text-lg);
  font-weight: 600;
  border: 1px solid transparent;
  transition: transform var(--transition), background var(--transition), box-shadow var(--transition);
  text-decoration: none;
  min-width: 180px;
  justify-content: center;
}

.download-btn:hover {
  background: var(--brand-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.download-icon {
  font-size: var(--text-xl);
}

.download-text {
  font-weight: 600;
}

/* ==========================================================================
   頁尾
   ========================================================================== */
footer {
  border-top: 1px solid var(--border);
  padding-block: var(--spacing-2xl);
  text-align: center;
}

footer p {
  color: var(--muted);
  font-size: var(--text-base);
}

/* ==========================================================================
   響應式
   ========================================================================== */
@media (max-width: 980px) {
  .video-hero { min-height: calc(70vh - var(--navbar-height)); }
  .video-hero .container { gap: 30px; }
  .video-hero .hero-title { font-size: var(--text-4xl); }
  .video-hero .hero-subtitle { font-size: var(--text-xl); }

  .use-card.horizontal { min-height: 300px; }
  .use-card.horizontal img {
    inline-size: clamp(280px, 50vw, 420px);
    block-size: 280px;
  }
  .use-card.horizontal .use-content { padding: 45px; }

  /* 功能特色 - 平板版 */
  .features { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  .steps::before { display: none; }

  .video-hero { min-height: calc(60vh - var(--navbar-height)); }
  .video-hero .container { gap: var(--spacing-lg); }
  .video-hero .hero-title { font-size: var(--text-3xl); }
  .video-hero .hero-subtitle { font-size: var(--text-lg); }

  .use-card.horizontal,
  .use-card.horizontal.reverse {
    flex-direction: column;
    min-height: auto;
  }

  .use-card.horizontal img {
    inline-size: 100%;
    block-size: 240px;
  }

  .use-card.horizontal .use-content { padding: 28px; }

  .download-buttons {
    flex-direction: column;
    gap: var(--spacing-md);
    align-items: center;
  }

  .download-btn {
    min-width: 200px;
    font-size: var(--text-base);
  }

  .hero-buttons { flex-direction: column; align-items: center; }
  .btn { inline-size: 200px; justify-content: center; }

  .section { padding-block: 60px; }
  .section-title { font-size: var(--text-3xl); margin-bottom: var(--spacing-2xl); }

  /* 問題解決方案卡片 - 手機版 */
  .problem-solution-card {
    padding: var(--spacing-2xl) var(--spacing-lg);
    margin-inline: var(--spacing-sm);
  }

  .problem-title { font-size: var(--text-2xl); }

  .solution-highlight { font-size: var(--text-xl); }

  .solution-description { font-size: var(--text-lg); }

  /* 功能特色 - 手機版 */
  .features { grid-template-columns: 1fr; gap: var(--spacing-lg); }
}

/* ==========================================================================
   Motion reduction / 動化減量
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  .feature-card:hover,
  .use-card:hover,
  .btn:hover,
  .nav-cta:hover { transform: none !important; }
}