/* ==========================================================================
   豆包官网 · 水墨泼墨晕染留白气韵流转 · 新中式水墨风
   色彩体系：徽州水墨黑 (#161615) + 生宣落日微黄 (#F8F3E6 / #F1E6CE / #D98E4E)
   骨架体系：虚实相生大留白骨架，文字漂浮于半透明墨晕边缘，滚动如水墨洇开
   ========================================================================== */

:root {
  /* 新中式水墨风核心色板 */
  --paper-base: #F8F3E6;          /* 生宣暖白底色 */
  --paper-warm: #F3EAD6;          /* 生宣落日微黄晕层 */
  --paper-card: rgba(252, 249, 242, 0.88); /* 半透明宣纸白卡 */
  --paper-solid: #FCF9F2;
  
  --ink-black: #161615;           /* 徽州水墨焦墨 */
  --ink-heavy: #2A2927;           /* 浓墨 */
  --ink-medium: #4A4843;          /* 重墨 */
  --ink-light: #736F67;           /* 淡墨 */
  --ink-faint: #9E988E;           /* 清墨 */
  
  --ink-wash-dark: rgba(22, 22, 21, 0.08);
  --ink-wash-soft: rgba(22, 22, 21, 0.04);
  --ink-border: rgba(22, 22, 21, 0.12);
  --ink-border-strong: rgba(22, 22, 21, 0.28);

  --sunset-amber: #C97A3E;        /* 落日微黄暖赭 */
  --sunset-glow: rgba(217, 142, 78, 0.18);
  --cinnabar-seal: #B83B2B;       /* 朱砂印泥红 */
  --purple-grid: rgba(114, 98, 138, 0.07); /* 浅紫网格微纹 */
  --purple-glow: rgba(132, 108, 168, 0.13); /* 顶部浅紫加落日微黄光晕 */

  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --radius-pill: 999px;

  --shadow-ink: 0 18px 48px -12px rgba(22, 22, 21, 0.09), 0 4px 14px rgba(22, 22, 21, 0.04);
  --shadow-hover: 0 24px 56px -12px rgba(22, 22, 21, 0.15), 0 6px 18px rgba(201, 122, 62, 0.08);
  
  --max-w: 1180px;
  --font-serif: "Songti SC", "Noto Serif SC", "STSong", "SimSun", "Source Han Serif SC", serif;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", Consolas, "Liberation Mono", monospace;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  background-color: var(--paper-base);
  color: var(--ink-black);
}

body {
  font-family: var(--font-sans);
  background-color: var(--paper-base);
  color: var(--ink-black);
  line-height: 1.75;
  overflow-x: hidden;
  position: relative;
  /* 生宣纸肌理与水墨晕染大留白背景 */
  background-image: 
    radial-gradient(ellipse 80% 50% at 50% 0%, var(--sunset-glow) 0%, transparent 70%),
    radial-gradient(circle at 15% 22%, rgba(22, 22, 21, 0.035) 0%, transparent 45%),
    radial-gradient(circle at 85% 48%, rgba(201, 122, 62, 0.06) 0%, transparent 50%),
    radial-gradient(circle at 20% 78%, rgba(22, 22, 21, 0.04) 0%, transparent 55%);
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.3s cubic-bezier(0.22, 1, 0.36, 1);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 28px;
}

/* ==========================================================================
   水墨泼墨晕染装饰与滚动洇开动效 (Ink Wash & Scroll Bleed)
   ========================================================================== */
.ink-bleed-section {
  position: relative;
  padding: 96px 0;
}

/* 半透明墨晕边缘漂浮感 */
.ink-halo-bg::before {
  content: "";
  position: absolute;
  width: 520px;
  height: 520px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(22, 22, 21, 0.055) 0%, rgba(217, 142, 78, 0.04) 45%, transparent 72%);
  filter: blur(36px);
  pointer-events: none;
  z-index: 0;
}

.ink-reveal {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.85s cubic-bezier(0.16, 1, 0.3, 1), transform 0.85s cubic-bezier(0.16, 1, 0.3, 1), filter 0.85s ease;
}

.js-ready .ink-reveal {
  opacity: 0;
  transform: translateY(22px) scale(0.99);
  filter: blur(4px);
}

.js-ready .ink-reveal.is-inked {
  opacity: 1;
  transform: translateY(0) scale(1);
  filter: blur(0);
}

/* 通用章节标题：文字漂浮于半透明墨晕边缘 */
.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 60px;
  position: relative;
  z-index: 1;
}

.section-header::before {
  content: "";
  position: absolute;
  top: -24px;
  left: 50%;
  transform: translateX(-50%);
  width: 240px;
  height: 90px;
  background: radial-gradient(ellipse at center, rgba(22, 22, 21, 0.06) 0%, rgba(217, 142, 78, 0.08) 50%, transparent 75%);
  filter: blur(16px);
  z-index: -1;
  pointer-events: none;
}

.ink-seal-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 16px;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--ink-heavy);
  background: rgba(243, 234, 214, 0.85);
  border: 1px solid var(--ink-border-strong);
  border-radius: var(--radius-pill);
  margin-bottom: 16px;
  box-shadow: 0 2px 10px rgba(22, 22, 21, 0.04);
}

.ink-seal-stamp {
  display: inline-block;
  padding: 1px 6px;
  font-size: 11px;
  color: #FFF;
  background: var(--cinnabar-seal);
  border-radius: 4px;
  font-family: var(--font-serif);
  letter-spacing: 0.05em;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(26px, 3.5vw, 38px);
  font-weight: 700;
  color: var(--ink-black);
  line-height: 1.3;
  letter-spacing: 0.02em;
  margin-bottom: 14px;
}

.section-desc {
  font-size: 16px;
  color: var(--ink-light);
  line-height: 1.75;
}

/* ==========================================================================
   1. 顶部导航
   左侧是圆形「豆」标和品牌名，右侧是「登录」文字链和胶囊按钮「开始使用」。
   窄屏时中间锚点收起，底部固定「下载 App」和「开始对话」。
   ========================================================================== */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: 70px;
  background: rgba(248, 243, 230, 0.86);
  backdrop-filter: saturate(1.6) blur(16px);
  -webkit-backdrop-filter: saturate(1.6) blur(16px);
  border-bottom: 1px solid var(--ink-border);
}

.nav-inner {
  max-width: var(--max-w);
  height: 100%;
  margin: 0 auto;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.brand-dou-circle {
  position: relative;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--ink-black);
  border: 2px solid var(--sunset-amber);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  box-shadow: 0 4px 12px rgba(22, 22, 21, 0.16);
  flex-shrink: 0;
}

.brand-dou-circle img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.brand-dou-badge {
  position: absolute;
  right: -2px;
  bottom: -2px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--cinnabar-seal);
  color: #FFF;
  font-family: var(--font-serif);
  font-size: 11px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1.5px solid var(--paper-base);
}

.brand-meta {
  display: flex;
  flex-direction: column;
}

.brand-name {
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 700;
  color: var(--ink-black);
  line-height: 1.2;
  letter-spacing: 0.03em;
  display: flex;
  align-items: center;
  gap: 6px;
}

.brand-sub {
  font-size: 12px;
  color: var(--ink-light);
}

.nav-anchors {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-link {
  font-size: 14.5px;
  color: var(--ink-medium);
  font-weight: 500;
  padding: 6px 2px;
  position: relative;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--ink-black), var(--sunset-amber));
  transition: width 0.3s ease;
}

.nav-link:hover,
.nav-link.active {
  color: var(--ink-black);
  font-weight: 600;
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 18px;
}

.nav-login-link {
  font-size: 14.5px;
  font-weight: 600;
  color: var(--ink-heavy);
  padding: 6px 10px;
}

.nav-login-link:hover {
  color: var(--sunset-amber);
}

.btn-capsule-start {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 9px 22px;
  border-radius: var(--radius-pill);
  background: linear-gradient(135deg, var(--ink-black) 0%, #332E2A 60%, var(--sunset-amber) 100%);
  color: #FCF9F2;
  font-size: 14px;
  font-weight: 600;
  box-shadow: 0 6px 18px rgba(22, 22, 21, 0.18);
}

.btn-capsule-start:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 24px rgba(22, 22, 21, 0.25);
}

/* ==========================================================================
   2. 首屏 (Hero)
   内容居中。最上是呼吸点徽章「AI 智能助手 · 多端同步 · 免费使用」，
   下面是大标题「豆包，你的 AI 助手」和两行副标题。
   再往下是圆角输入框，按钮嵌在框内，文案是「开始对话」。
   主按钮「免费开始使用」是满宽渐变，次按钮「下载 App」是白底线框。
   最底一行写支持网页、iOS、Android、Windows、macOS。
   背景是浅紫网格加顶部光晕（融合新中式水墨徽州水墨黑+生宣落日微黄）。
   ========================================================================== */
.hero-section {
  position: relative;
  padding: 76px 0 56px;
  overflow: hidden;
  /* 浅紫网格加顶部落日与墨韵光晕 */
  background-image:
    radial-gradient(circle at 50% 0%, var(--purple-glow) 0%, var(--sunset-glow) 38%, transparent 72%),
    linear-gradient(to right, var(--purple-grid) 1px, transparent 1px),
    linear-gradient(to bottom, var(--purple-grid) 1px, transparent 1px);
  background-size: 100% 100%, 36px 36px, 36px 36px;
  border-bottom: 1px solid var(--ink-border);
}

/* 水墨泼墨留白装饰晕圈 */
.hero-section::before {
  content: "";
  position: absolute;
  top: 40px;
  left: 8%;
  width: 340px;
  height: 340px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(22, 22, 21, 0.07) 0%, rgba(22, 22, 21, 0.02) 55%, transparent 75%);
  filter: blur(22px);
  pointer-events: none;
}

.hero-section::after {
  content: "";
  position: absolute;
  bottom: 10%;
  right: 6%;
  width: 400px;
  height: 400px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(217, 142, 78, 0.14) 0%, rgba(22, 22, 21, 0.04) 55%, transparent 75%);
  filter: blur(28px);
  pointer-events: none;
}

.hero-center-box {
  max-width: 780px;
  margin: 0 auto;
  text-align: center;
  position: relative;
  z-index: 2;
}

.breathing-badge {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 7px 20px;
  border-radius: var(--radius-pill);
  background: rgba(252, 249, 242, 0.9);
  border: 1px solid var(--ink-border-strong);
  font-size: 13.5px;
  font-weight: 600;
  color: var(--ink-heavy);
  margin-bottom: 26px;
  box-shadow: 0 4px 16px rgba(22, 22, 21, 0.05);
}

.breathing-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--cinnabar-seal);
  box-shadow: 0 0 0 0 rgba(184, 59, 43, 0.6);
  animation: inkPulse 2.2s infinite;
}

@keyframes inkPulse {
  0% { box-shadow: 0 0 0 0 rgba(184, 59, 43, 0.55); }
  70% { box-shadow: 0 0 0 9px rgba(184, 59, 43, 0); }
  100% { box-shadow: 0 0 0 0 rgba(184, 59, 43, 0); }
}

.hero-h1 {
  font-family: var(--font-serif);
  font-size: clamp(34px, 5vw, 56px);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: -0.01em;
  margin-bottom: 12px;
  background: linear-gradient(120deg, var(--ink-black) 0%, #3A322D 48%, var(--sunset-amber) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-h1-sub {
  display: block;
  font-size: clamp(18px, 2.4vw, 24px);
  font-weight: 600;
  color: var(--ink-heavy);
  -webkit-text-fill-color: var(--ink-heavy);
  margin-top: 8px;
  letter-spacing: 0.04em;
}

.hero-subtitle {
  font-size: 17.5px;
  color: var(--ink-medium);
  line-height: 1.8;
  max-width: 680px;
  margin: 18px auto 30px;
}

/* 圆角输入框，按钮嵌在框内，文案「开始对话」 */
.hero-input-bar {
  display: flex;
  align-items: center;
  max-width: 660px;
  margin: 0 auto 22px;
  padding: 7px 8px 7px 22px;
  background: var(--paper-solid);
  border: 1.5px solid var(--ink-border-strong);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-ink);
  transition: border-color 0.25s, box-shadow 0.25s;
}

.hero-input-bar:focus-within {
  border-color: var(--ink-black);
  box-shadow: 0 12px 34px rgba(22, 22, 21, 0.14);
}

.hero-input-field {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  font-size: 15.5px;
  color: var(--ink-black);
  font-family: inherit;
  min-width: 0;
}

.hero-input-field::placeholder {
  color: var(--ink-faint);
}

.hero-embed-btn {
  padding: 11px 26px;
  border: none;
  border-radius: var(--radius-pill);
  background: var(--ink-black);
  color: #FCF9F2;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  flex-shrink: 0;
  transition: background 0.25s, transform 0.2s;
}

.hero-embed-btn:hover {
  background: var(--sunset-amber);
  transform: translateY(-1px);
}

/* 主按钮「免费开始使用」满宽渐变，次按钮「下载 App」白底线框 */
.hero-cta-group {
  max-width: 660px;
  margin: 0 auto 22px;
  display: grid;
  grid-template-columns: 1.35fr 1fr;
  gap: 14px;
}

.btn-primary-gradient {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 15px 28px;
  border-radius: var(--radius-pill);
  background: linear-gradient(135deg, #161615 0%, #3B322C 52%, #C97A3E 100%);
  color: #FCF9F2;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.03em;
  box-shadow: 0 10px 26px rgba(22, 22, 21, 0.2);
  border: none;
  cursor: pointer;
}

.btn-primary-gradient:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 32px rgba(22, 22, 21, 0.28);
}

.btn-secondary-outline {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 15px 28px;
  border-radius: var(--radius-pill);
  background: var(--paper-solid);
  color: var(--ink-black);
  border: 1.5px solid var(--ink-border-strong);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
}

.btn-secondary-outline:hover {
  border-color: var(--ink-black);
  background: var(--paper-warm);
  transform: translateY(-2px);
}

.hero-platforms-note {
  font-size: 13.5px;
  color: var(--ink-light);
  letter-spacing: 0.04em;
}

/* ==========================================================================
   3. 对话预览 (首屏下方拟态对话卡)
   用户先要求把产品介绍压到 80 字，豆包给出改写；用户再要求更口语化。
   用来演示「怎么问、怎么答」。
   ========================================================================== */
.dialogue-preview-wrap {
  max-width: 920px;
  margin: 44px auto 0;
  position: relative;
  z-index: 2;
}

.dialogue-mock-card {
  background: var(--paper-card);
  border: 1px solid var(--ink-border-strong);
  border-radius: 24px;
  box-shadow: var(--shadow-ink);
  overflow: hidden;
  backdrop-filter: blur(12px);
}

.mock-window-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 22px;
  background: rgba(22, 22, 21, 0.04);
  border-bottom: 1px solid var(--ink-border);
}

.window-dots {
  display: flex;
  gap: 8px;
}

.win-dot {
  width: 11px;
  height: 11px;
  border-radius: 50%;
}

.win-dot.red { background: #C85A4B; }
.win-dot.yellow { background: #D99B4E; }
.win-dot.green { background: #5A8F69; }

.window-title {
  font-size: 13px;
  color: var(--ink-medium);
  font-weight: 600;
  letter-spacing: 0.04em;
}

.window-status {
  font-size: 12px;
  color: var(--sunset-amber);
  font-weight: 600;
}

.dialogue-stream {
  padding: 28px 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
  text-align: left;
}

.chat-row {
  display: flex;
  gap: 14px;
  align-items: flex-start;
}

.chat-row.user {
  justify-content: flex-end;
}

.chat-avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 700;
  background: var(--ink-black);
  color: #FCF9F2;
  overflow: hidden;
  border: 1px solid var(--sunset-amber);
}

.chat-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.chat-bubble {
  max-width: 78%;
  padding: 14px 18px;
  border-radius: 16px;
  font-size: 14.5px;
  line-height: 1.7;
}

.chat-row.user .chat-bubble {
  background: var(--ink-black);
  color: #FCF9F2;
  border-bottom-right-radius: 4px;
}

.chat-row.ai .chat-bubble {
  background: var(--paper-solid);
  color: var(--ink-black);
  border: 1px solid var(--ink-border-strong);
  border-bottom-left-radius: 4px;
}

.chat-meta-tag {
  display: inline-block;
  font-size: 11.5px;
  color: var(--sunset-amber);
  font-weight: 600;
  margin-bottom: 4px;
}

.dialogue-visual-showcase {
  margin-top: 26px;
  padding: 16px;
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-ink);
}

.dialogue-visual-showcase img {
  width: 100%;
  border-radius: 12px;
}

.showcase-caption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-light);
  text-align: center;
}

/* ==========================================================================
   4. 信任条
   四句横排：多端同步、传输加密、中文场景优化、未成年人保护。没有大图标堆砌。
   ========================================================================== */
.trust-strip {
  background: var(--paper-warm);
  border-bottom: 1px solid var(--ink-border);
  padding: 20px 0;
}

.trust-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  text-align: center;
}

.trust-item {
  font-size: 14.5px;
  font-weight: 600;
  color: var(--ink-heavy);
  padding: 6px 12px;
  border-right: 1px solid var(--ink-border);
  letter-spacing: 0.03em;
}

.trust-item:last-child {
  border-right: none;
}

.trust-item span {
  display: block;
  font-size: 12.5px;
  color: var(--ink-light);
  font-weight: 400;
  margin-top: 2px;
}

/* ==========================================================================
   5. 能力矩阵
   标题是「一个豆包，搞定八种常用能力」。
   八张白卡：AI 对话、写作助手、多语翻译、编程开发、图像生成、语音通话、文件阅读、智能体。
   每张是标题加两行说明。
   ========================================================================== */
.matrix-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 22px;
}

.white-ink-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  position: relative;
  transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
  box-shadow: 0 4px 16px rgba(22, 22, 21, 0.03);
}

.white-ink-card::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 72px;
  height: 72px;
  background: radial-gradient(circle at top right, rgba(22, 22, 21, 0.05), transparent 70%);
  border-top-right-radius: var(--radius-lg);
  pointer-events: none;
}

.white-ink-card:hover {
  transform: translateY(-5px);
  border-color: var(--ink-border-strong);
  box-shadow: var(--shadow-hover);
}

.card-ink-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: rgba(22, 22, 21, 0.05);
  border: 1px solid var(--ink-border);
  color: var(--ink-black);
  font-family: var(--font-serif);
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 18px;
}

.card-title {
  font-family: var(--font-serif);
  font-size: 19px;
  font-weight: 700;
  color: var(--ink-black);
  margin-bottom: 10px;
}

.card-two-lines {
  font-size: 14.5px;
  color: var(--ink-medium);
  line-height: 1.65;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 14px;
}

.card-more-link {
  font-size: 13px;
  font-weight: 600;
  color: var(--sunset-amber);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* ==========================================================================
   6. 场景
   按身份分块：学习、工作、创作、编程、生活。每块有英文小标，再加可直接照抄的提问。
   ========================================================================== */
.scenarios-bg {
  background: var(--paper-warm);
  border-top: 1px solid var(--ink-border);
  border-bottom: 1px solid var(--ink-border);
}

.scenarios-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}

.scenario-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.scenario-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.scenario-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px dashed var(--ink-border-strong);
}

.scenario-cn {
  font-family: var(--font-serif);
  font-size: 21px;
  font-weight: 700;
  color: var(--ink-black);
}

.scenario-en {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--sunset-amber);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.copy-prompt-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.copy-prompt-item {
  padding: 10px 14px;
  background: var(--paper-base);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  color: var(--ink-heavy);
  line-height: 1.55;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
}

.copy-prompt-item:hover {
  border-color: var(--sunset-amber);
  background: #FFFDF8;
}

.scenario-banner-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border-strong);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.scenario-banner-card img {
  border-radius: 12px;
  margin-bottom: 12px;
}

/* ==========================================================================
   7. 问答示例
   三列卡片，覆盖职场写作、编程调试、长文总结。上句是用户输入，下句是系统交付。
   ========================================================================== */
.qa-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.qa-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-lg);
  padding: 26px 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  box-shadow: var(--shadow-ink);
}

.qa-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.qa-tag {
  padding: 3px 12px;
  border-radius: var(--radius-pill);
  background: var(--ink-black);
  color: #FCF9F2;
  font-size: 12px;
  font-weight: 600;
}

.qa-user-box {
  padding: 14px 16px;
  background: var(--paper-warm);
  border-left: 3px solid var(--ink-black);
  border-radius: 8px;
  font-size: 14px;
  color: var(--ink-black);
  font-weight: 600;
}

.qa-ai-box {
  padding: 14px 16px;
  background: var(--paper-base);
  border: 1px solid var(--ink-border);
  border-radius: 8px;
  font-size: 13.5px;
  color: var(--ink-medium);
  line-height: 1.7;
  flex: 1;
}

/* ==========================================================================
   8. 下载
   说明同一账号多端同步，并配扫码去应用商店。和首屏的「下载 App」是同一条路径。
   ========================================================================== */
.download-section {
  background: var(--paper-warm);
  border-top: 1px solid var(--ink-border);
  border-bottom: 1px solid var(--ink-border);
}

.download-split {
  display: grid;
  grid-template-columns: 330px 1fr;
  gap: 28px;
  align-items: stretch;
}

.qr-panel {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border-strong);
  border-radius: var(--radius-lg);
  padding: 32px 26px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-ink);
}

.qr-code-box {
  width: 156px;
  height: 156px;
  padding: 14px;
  background: #FFF;
  border: 2px solid var(--ink-black);
  border-radius: 16px;
  margin: 16px 0;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
  gap: 5px;
}

.qr-pixel {
  background: var(--ink-black);
  border-radius: 2px;
}

.qr-pixel.light {
  background: var(--sunset-amber);
}

.qr-pixel.blank {
  background: transparent;
}

.platforms-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.platform-dl-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-md);
  padding: 22px 20px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: transform 0.25s, border-color 0.25s;
}

.platform-dl-card:hover {
  transform: translateY(-4px);
  border-color: var(--ink-black);
}

.platform-dl-card h3 {
  font-family: var(--font-serif);
  font-size: 18px;
  margin-bottom: 6px;
}

.platform-dl-card p {
  font-size: 13.5px;
  color: var(--ink-light);
  margin-bottom: 16px;
}

.platform-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 16px;
  border-radius: var(--radius-pill);
  background: var(--ink-black);
  color: #FCF9F2;
  font-size: 13px;
  font-weight: 600;
}

.platform-btn:hover {
  background: var(--sunset-amber);
}

/* ==========================================================================
   9. 技术底座
   四列，序号 01 到 04：语言理解、语音交互、图像、智能体。比上面的能力卡更短。
   ========================================================================== */
.tech-grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.tech-short-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-md);
  padding: 22px 20px;
}

.tech-num {
  font-family: var(--font-serif);
  font-size: 28px;
  font-weight: 800;
  color: var(--sunset-amber);
  line-height: 1.1;
  margin-bottom: 8px;
}

.tech-short-card h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 6px;
}

.tech-short-card p {
  font-size: 13.5px;
  color: var(--ink-light);
  line-height: 1.6;
}

/* ==========================================================================
   10. 评价
   三列引用：在校研究生、互联网运营、后端工程师。页内写明这些是示例，上线前要换成授权评价。
   ========================================================================== */
.review-disclaimer {
  text-align: center;
  font-size: 13px;
  color: var(--cinnabar-seal);
  background: rgba(184, 59, 43, 0.08);
  border: 1px solid rgba(184, 59, 43, 0.25);
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  display: table;
  margin: -32px auto 36px;
}

.reviews-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}

.review-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.review-text {
  font-size: 14.5px;
  color: var(--ink-heavy);
  line-height: 1.75;
  margin-bottom: 20px;
}

.review-user {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-top: 14px;
  border-top: 1px solid var(--ink-border);
}

.review-avatar {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: var(--ink-black);
  color: #FCF9F2;
  font-family: var(--font-serif);
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ==========================================================================
   11. 安全
   六块说明：加密、隐私政策、内容安全、未成年人保护、用户协议、举报入口。
   做成产品模块，不是一整面法律文。
   ========================================================================== */
.security-grid-6 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.security-module-card {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border);
  border-radius: var(--radius-md);
  padding: 24px 22px;
}

.security-badge {
  display: inline-block;
  padding: 3px 10px;
  font-size: 12px;
  font-weight: 700;
  color: var(--ink-black);
  background: var(--paper-warm);
  border: 1px solid var(--ink-border-strong);
  border-radius: 6px;
  margin-bottom: 12px;
}

.security-module-card h3 {
  font-family: var(--font-serif);
  font-size: 18px;
  margin-bottom: 8px;
}

.security-module-card p {
  font-size: 13.5px;
  color: var(--ink-light);
  line-height: 1.65;
}

/* ==========================================================================
   12. 常见问题
   四个类别：产品认知、功能使用、下载与多端、安全与隐私。每条回答拆成四步。
   ========================================================================== */
.faq-narrow-wrap {
  max-width: 860px;
  margin: 0 auto;
}

.faq-category-tabs {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-bottom: 28px;
}

.faq-cat-pill {
  padding: 6px 16px;
  border-radius: var(--radius-pill);
  background: var(--paper-solid);
  border: 1px solid var(--ink-border-strong);
  font-size: 13.5px;
  font-weight: 600;
  color: var(--ink-heavy);
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-details {
  background: var(--paper-solid);
  border: 1px solid var(--ink-border-strong);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.faq-summary {
  padding: 20px 24px;
  font-size: 16.5px;
  font-weight: 700;
  color: var(--ink-black);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  list-style: none;
}

.faq-summary::-webkit-details-marker {
  display: none;
}

.faq-cat-label {
  font-size: 12px;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: var(--radius-pill);
  background: var(--paper-warm);
  color: var(--sunset-amber);
  margin-right: 10px;
}

.faq-steps-grid {
  padding: 0 24px 22px;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  border-top: 1px dashed var(--ink-border);
  padding-top: 18px;
}

.faq-step-box {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 12px;
  background: var(--paper-base);
  border-radius: 10px;
  font-size: 13.5px;
  color: var(--ink-medium);
}

.step-circle {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--ink-black);
  color: #FCF9F2;
  font-size: 12px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 2px;
}

/* ==========================================================================
   13. 收口与页脚
   末段是「现在就开始使用豆包」，把人送回对话或下载。
   ========================================================================== */
.closing-cta-section {
  background: linear-gradient(160deg, #161615 0%, #26221E 60%, #3A2D23 100%);
  color: #FCF9F2;
  padding: 84px 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.closing-cta-box {
  max-width: 720px;
  margin: 0 auto;
  position: relative;
  z-index: 2;
}

.closing-cta-title {
  font-family: var(--font-serif);
  font-size: clamp(28px, 4vw, 42px);
  font-weight: 700;
  margin-bottom: 16px;
  color: #FCF9F2;
}

.closing-cta-desc {
  font-size: 16px;
  color: rgba(252, 249, 242, 0.78);
  margin-bottom: 32px;
}

.closing-btn-row {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.site-footer {
  background: #0F1220;
  color: rgba(248, 243, 230, 0.78);
  padding: 64px 0 36px;
  font-size: 14px;
}

.footer-top-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 36px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(248, 243, 230, 0.12);
}

.footer-brand-title {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-serif);
  font-size: 19px;
  font-weight: 700;
  color: #FCF9F2;
  margin-bottom: 12px;
}

.footer-brand-title img {
  width: 34px;
  height: 34px;
  border-radius: 50%;
}

.footer-col h4 {
  color: #FCF9F2;
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 14px;
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-col a {
  color: rgba(248, 243, 230, 0.7);
}

.footer-col a:hover {
  color: var(--sunset-amber);
}

.footer-bottom-bar {
  padding-top: 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 14px;
  font-size: 13px;
  color: rgba(248, 243, 230, 0.55);
}

/* ==========================================================================
   窄屏底部固定双按钮条「下载 App」和「开始对话」
   ========================================================================== */
.mobile-fixed-bar {
  display: none;
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 120;
  padding: 10px 16px calc(10px + env(safe-area-inset-bottom));
  background: rgba(248, 243, 230, 0.96);
  backdrop-filter: blur(14px);
  border-top: 1px solid var(--ink-border-strong);
  grid-template-columns: 1fr 1.25fr;
  gap: 12px;
  box-shadow: 0 -6px 24px rgba(22, 22, 21, 0.1);
}

.mobile-fixed-bar a {
  padding: 12px 14px;
  border-radius: var(--radius-pill);
  font-size: 14.5px;
  font-weight: 700;
  text-align: center;
}

.mobile-btn-dl {
  background: var(--paper-solid);
  color: var(--ink-black);
  border: 1.5px solid var(--ink-black);
}

.mobile-btn-chat {
  background: linear-gradient(135deg, var(--ink-black), var(--sunset-amber));
  color: #FCF9F2;
}

/* ==========================================================================
   响应式适配 (1080px / 900px / 640px)
   ========================================================================== */
@media (max-width: 1080px) {
  .matrix-grid,
  .tech-grid-4,
  .trust-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .scenarios-grid,
  .qa-grid-3,
  .reviews-grid-3,
  .security-grid-6 {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 900px) {
  .nav-anchors {
    display: none;
  }
  .download-split {
    grid-template-columns: 1fr;
  }
  .platforms-grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-top-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 640px) {
  body {
    padding-bottom: 74px;
  }
  .ink-bleed-section {
    padding: 64px 0;
  }
  .hero-cta-group,
  .matrix-grid,
  .scenarios-grid,
  .qa-grid-3,
  .platforms-grid-3,
  .tech-grid-4,
  .reviews-grid-3,
  .security-grid-6,
  .trust-grid,
  .faq-steps-grid,
  .footer-top-grid {
    grid-template-columns: 1fr;
  }
  .hero-input-bar {
    flex-direction: column;
    border-radius: 18px;
    padding: 12px;
    gap: 10px;
  }
  .hero-input-field {
    width: 100%;
    padding: 6px 8px;
  }
  .hero-embed-btn {
    width: 100%;
  }
  .trust-item {
    border-right: none;
    border-bottom: 1px solid var(--ink-border);
    padding-bottom: 10px;
  }
  .trust-item:last-child {
    border-bottom: none;
  }
  .mobile-fixed-bar {
    display: grid;
  }
}