/* ==========================================================================
   通义千问 - 精装书切口与书口灰阶设计系统 (Hardcover Book Fore-Edge Grayscale Style)
   风格：精装书 (Hardcover Book)
   场景：能力介绍与全栈大模型架构
   核心规则：
   1. 布局：页面右侧做出书口染色（Fore-Edge Staining），不同章节是不同灰度的切口，正文始终单栏
   2. 风格说明：精装书内页：切口只有灰阶，封面绝对不出现
   3. 字体体系：章节名宋体 (Songti SC / SimSun / STSong)，正文宋体，英文规范衬线
   4. 标注规范：切口旁注「千问」、「千问网页版」、「千问办公」、「qwen」，书名页标注「通义千问」
   5. 视觉禁忌：严禁使用任何烫金与花纹环衬，纯粹质朴高级的精装书籍内页石墨灰阶美学
   ========================================================================== */

:root {
  /* 纯正宋体与精装书字体族 */
  --font-songti: "Songti SC", "Source Han Serif SC", "SimSun", "STSong", "Noto Serif SC", serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace;

  /* 精装书内页经典纸色与灰阶系统（绝对无烫金、无花纹） */
  --color-page-bg: #f9f8f4;          /* 典雅精装书内页纸白 */
  --color-page-card: #f3f1ea;        /* 书叶微暗衬底 */
  --color-page-pure: #ffffff;        /* 亮面纸底 */
  --color-ink-black: #111111;        /* 活字印墨黑 */
  --color-ink-prose: #2a2927;        /* 正文墨色 */
  --color-ink-annotation: #595650;   /* 旁注炭灰 */
  --color-ink-muted: #88847d;        /* 极淡页码灰 */
  
  --color-book-rule: #111111;        /* 精装书重压裁线 */
  --color-book-crease: #dbd6cc;      /* 书叶装订线 */

  /* 右侧书口灰阶染色层级（不同章节不同灰度，纯灰阶，绝无杂色） */
  --edge-gray-1: #2b2b2b;            /* 章节一切口：深炭黑灰阶 */
  --edge-gray-2: #525252;            /* 章节二切口：石墨中灰阶 */
  --edge-gray-3: #7a7a7a;            /* 章节三切口：铅印浅灰阶 */
  --edge-gray-4: #a3a3a3;            /* 章节四切口：淡雾淡灰阶 */

  --container-max: 1220px;
}

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

body {
  background-color: var(--color-page-bg);
  color: var(--color-ink-prose);
  font-family: var(--font-songti);
  line-height: 1.85;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.layout-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-songti);
  color: var(--color-ink-black);
  font-weight: 700;
  line-height: 1.35;
}

a {
  color: inherit;
  text-decoration: none;
  transition: opacity 0.2s ease, color 0.2s ease;
}

/* ==========================================================================
   1. 顶栏：标志、七个锚点、登录、开始使用
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(249, 248, 244, 0.98);
  backdrop-filter: blur(8px);
  border-bottom: 2px solid var(--color-book-rule);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  gap: 16px;
}

.brand-wrapper {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-logo-frame {
  width: 36px;
  height: 36px;
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-pure);
  display: flex;
  align-items: center;
  justify-content: center;
}

.brand-logo {
  width: 22px;
  height: 22px;
  object-fit: contain;
  display: block;
}

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

.brand-title {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--color-ink-black);
  letter-spacing: 0.05em;
  line-height: 1.15;
}

.brand-sub {
  font-size: 0.68rem;
  color: var(--color-ink-muted);
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.nav-anchors {
  display: flex;
  list-style: none;
  gap: 20px;
  align-items: center;
}

.nav-link {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--color-ink-prose);
  padding: 6px 2px;
  position: relative;
}

.nav-link:hover {
  color: var(--color-ink-black);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 1.5px;
  background: var(--color-book-rule);
  transition: width 0.25s ease;
}

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

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.btn-header-login {
  padding: 6px 14px;
  font-size: 0.86rem;
  color: var(--color-ink-black);
  border: 1px solid var(--color-book-crease);
  background: var(--color-page-pure);
  font-weight: 600;
}

.btn-header-login:hover {
  border-color: var(--color-book-rule);
  background: var(--color-page-card);
}

.btn-header-primary {
  padding: 6px 16px;
  font-size: 0.86rem;
  background: var(--color-book-rule);
  color: #ffffff;
  border: 1px solid var(--color-book-rule);
  font-weight: 600;
}

.btn-header-primary:hover {
  background: #333333;
}

/* ==========================================================================
   2. 首屏：状态标签、标题、一句说明、一条提问框
   ========================================================================== */
.hero-section {
  padding: 48px 0 36px;
  border-bottom: 2px solid var(--color-book-rule);
}

.hero-status-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 18px;
  flex-wrap: wrap;
  gap: 12px;
  border-bottom: 1px dashed var(--color-book-crease);
  padding-bottom: 12px;
}

.hero-status-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--color-ink-black);
  letter-spacing: 0.04em;
}

.hero-spec-tag {
  font-size: 0.74rem;
  font-family: var(--font-mono);
  color: var(--color-ink-muted);
  letter-spacing: 0.08em;
}

.hero-title-box {
  margin-bottom: 18px;
}

.hero-h1 {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--color-ink-black);
  line-height: 1.32;
  letter-spacing: -0.02em;
}

.hero-desc {
  font-size: 1.08rem;
  color: var(--color-ink-annotation);
  max-width: 980px;
  margin-bottom: 28px;
  line-height: 1.85;
}

.hero-search-box {
  margin-bottom: 36px;
}

.hero-search-form {
  display: flex;
  max-width: 860px;
  border: 2px solid var(--color-book-rule);
  background: var(--color-page-pure);
  box-shadow: 4px 4px 0px rgba(17, 17, 17, 0.9);
}

.hero-search-input {
  flex: 1;
  border: none;
  outline: none;
  padding: 16px 20px;
  font-size: 0.96rem;
  font-family: var(--font-songti);
  color: var(--color-ink-black);
  background: transparent;
}

.hero-search-btn {
  background: var(--color-book-rule);
  color: #ffffff;
  border: none;
  padding: 0 28px;
  font-size: 0.94rem;
  font-family: var(--font-songti);
  font-weight: 700;
  cursor: pointer;
  transition: background 0.2s ease;
  white-space: nowrap;
}

.hero-search-btn:hover {
  background: #333333;
}

/* ==========================================================================
   ★ 核心视觉风格：精装书切口核心舞台 (Hardcover Fore-Edge Staining)
   风格：精装书内页
   场景：能力介绍
   布局：页面右侧做出书口染色，不同章节是不同灰度的切口，正文始终单栏，不出现封面
   风格说明：精装书：切口只有灰阶，封面不出现
   提示词：
   风格种「精装书」。用精装书的切口来组织千问AI能力。布局：右侧书口按章节染成不同灰度，正文始终单栏，不出现封面。风格：精装书内页，切口只用灰阶。字体：章节名宋体。切口旁注千问、千问网页版、千问办公、qwen，书名页写通义千问。不要烫金和花纹环衬。
   ========================================================================== */
.fore-edge-stage-container {
  background: var(--color-page-pure);
  border: 2px solid var(--color-book-rule);
  margin-top: 32px;
  box-shadow: 6px 6px 0px rgba(17, 17, 17, 0.85);
  position: relative;
  overflow: hidden;
}

/* 书名页顶栏：书名页写「通义千问」（严格无烫金、无花纹） */
.half-title-page-banner {
  padding: 14px 28px;
  border-bottom: 2px solid var(--color-book-rule);
  background: var(--color-page-card);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.half-title-book-name {
  font-family: var(--font-songti);
  font-size: 1.35rem;
  font-weight: 900;
  letter-spacing: 0.18em;
  color: var(--color-ink-black);
}

.half-title-meta {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--color-ink-annotation);
  letter-spacing: 0.08em;
}

/* 精装书核心对开双部：正文始终单栏 + 右侧书口灰阶染色切口 */
.book-spine-layout-wrapper {
  display: grid;
  grid-template-columns: 1fr 140px; /* 正文单栏 + 右侧切口 */
  min-height: 520px;
}

/* 核心：正文始终单栏 (Single-Column Prose Body) */
.book-single-column-prose {
  padding: 36px 40px;
  border-right: 2px solid var(--color-book-rule);
  background: var(--color-page-pure);
  display: flex;
  flex-direction: column;
  gap: 32px;
}

/* 章节项：章节名一律宋体 */
.chapter-prose-block {
  padding-bottom: 24px;
  border-bottom: 1px dashed var(--color-book-crease);
}

.chapter-prose-block:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.chapter-heading-songti {
  font-family: var(--font-songti);
  font-size: 1.38rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.chapter-num-badge {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  padding: 2px 8px;
  background: #111111;
  color: #ffffff;
  font-weight: 700;
}

.chapter-p-songti {
  font-family: var(--font-songti);
  font-size: 0.98rem;
  line-height: 1.95;
  color: var(--color-ink-prose);
  text-align: justify;
  margin-bottom: 10px;
}

.chapter-p-songti:last-child {
  margin-bottom: 0;
}

.chapter-p-songti strong {
  font-weight: 700;
  color: var(--color-ink-black);
}

/* 核心：右侧书口染色切口（Fore-Edge Staining - 纯灰阶，不同灰度，切口旁注） */
.fore-edge-stain-gutter {
  display: flex;
  flex-direction: column;
  background: #e8e4db; /* 书切口侧面纸张紧压质感 */
}

/* 四段切口横向色阶块：切口旁注千问、千问网页版、千问办公、qwen */
.edge-cut-segment {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 12px 8px;
  color: #ffffff;
  text-align: center;
  position: relative;
  border-bottom: 1px solid rgba(255, 255, 255, 0.25);
  transition: opacity 0.2s ease;
}

.edge-cut-segment:last-child {
  border-bottom: none;
}

/* 灰阶染色阶梯：只有灰阶，绝无金色或彩色 */
.edge-cut-segment.cut-1 {
  background-color: var(--edge-gray-1); /* #2b2b2b */
}

.edge-cut-segment.cut-2 {
  background-color: var(--edge-gray-2); /* #525252 */
}

.edge-cut-segment.cut-3 {
  background-color: var(--edge-gray-3); /* #7a7a7a */
}

.edge-cut-segment.cut-4 {
  background-color: var(--edge-gray-4); /* #a3a3a3 */
}

/* 切口旁注：宋体与等宽排布 */
.edge-margin-note {
  font-family: var(--font-songti);
  font-size: 0.92rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  margin-bottom: 4px;
  line-height: 1.25;
}

.edge-latin-note {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  opacity: 0.9;
  text-transform: uppercase;
}

/* 书底页码与版本脚线 */
.book-bottom-colophon {
  border-top: 1px solid var(--color-book-rule);
  padding: 10px 28px;
  background: var(--color-page-card);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--color-ink-muted);
}

/* ==========================================================================
   3. 信任：客户名和四个数字
   ========================================================================== */
.trust-section {
  padding: 44px 0;
  border-bottom: 1px solid var(--color-book-crease);
  background: var(--color-page-bg);
}

.trust-clients-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 32px;
  padding-bottom: 20px;
  border-bottom: 1px dashed var(--color-book-crease);
}

.trust-label {
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--color-ink-black);
  letter-spacing: 0.08em;
}

.trust-client-item {
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--color-ink-prose);
  border: 1px solid var(--color-book-crease);
  padding: 4px 12px;
  background: var(--color-page-card);
}

.metrics-4-col {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.metric-card {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
  padding: 24px 20px;
  box-shadow: 3px 3px 0px rgba(17, 17, 17, 0.6);
}

.metric-number {
  font-size: 2.2rem;
  font-weight: 900;
  color: var(--color-ink-black);
  line-height: 1.1;
  margin-bottom: 8px;
  font-family: var(--font-mono);
}

.metric-label {
  font-size: 0.88rem;
  color: var(--color-ink-annotation);
  line-height: 1.6;
}

/* ==========================================================================
   4. 能力：4 列 × 2 行，只有图标、标题和两行字
   ========================================================================== */
.capabilities-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
}

.section-head-bar {
  margin-bottom: 36px;
  border-bottom: 2px solid var(--color-book-rule);
  padding-bottom: 14px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.section-tag {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--color-ink-black);
  letter-spacing: 0.1em;
}

.section-h2 {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--color-ink-black);
  letter-spacing: -0.01em;
}

.cap-grid-4x2 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-auto-rows: 1fr;
  gap: 20px;
}

.cap-card-item {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
  padding: 22px 18px;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.cap-card-item:hover {
  transform: translateY(-2px);
  box-shadow: 4px 4px 0px rgba(17, 17, 17, 0.8);
}

.cap-icon {
  font-size: 1.5rem;
  color: var(--color-ink-black);
  margin-bottom: 12px;
  line-height: 1;
}

.cap-title {
  font-size: 1.05rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 8px;
}

.cap-line-1, .cap-line-2 {
  font-size: 0.85rem;
  color: var(--color-ink-annotation);
  line-height: 1.6;
}

/* ==========================================================================
   5. 目录：两组，每组 3 张卡，带状态和「试用 / 文档」
   ========================================================================== */
.catalog-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
  background: var(--color-page-bg);
}

.catalog-group-wrapper {
  margin-bottom: 40px;
}

.catalog-group-wrapper:last-child {
  margin-bottom: 0;
}

.group-header-label {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 18px;
  padding-left: 10px;
  border-left: 4px solid var(--color-ink-black);
  letter-spacing: 0.05em;
}

.catalog-cards-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.catalog-card {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
  padding: 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

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

.card-status-badge {
  font-size: 0.74rem;
  padding: 2px 8px;
  background: #e2ded5;
  color: var(--color-ink-black);
  font-weight: 700;
  border: 1px solid var(--color-book-crease);
}

.card-status-badge.hot {
  background: var(--color-ink-black);
  color: #ffffff;
  border-color: var(--color-ink-black);
}

.card-title {
  font-size: 1.12rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 10px;
}

.card-desc {
  font-size: 0.88rem;
  color: var(--color-ink-annotation);
  line-height: 1.7;
  margin-bottom: 20px;
}

.card-btn-duo {
  display: flex;
  gap: 12px;
  margin-top: auto;
}

.btn-trial {
  flex: 1;
  text-align: center;
  padding: 8px 12px;
  font-size: 0.84rem;
  font-weight: 700;
  background: var(--color-book-rule);
  color: #ffffff;
  border: 1px solid var(--color-book-rule);
}

.btn-trial:hover {
  background: #333333;
}

.btn-doc {
  flex: 1;
  text-align: center;
  padding: 8px 12px;
  font-size: 0.84rem;
  font-weight: 700;
  background: var(--color-page-pure);
  color: var(--color-ink-black);
  border: 1px solid var(--color-book-rule);
}

.btn-doc:hover {
  background: var(--color-page-card);
}

/* ==========================================================================
   6. 场景：3 列 × 2 行 (嵌入 1.webp ~ 4.webp)
   ========================================================================== */
.scenes-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
}

.scenes-grid-3x2 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.scene-card {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.scene-image-wrapper {
  width: 100%;
  height: 190px;
  overflow: hidden;
  background: #e8e4db;
  border-bottom: 1px solid var(--color-book-rule);
}

.scene-img {
  width: 380px;
  height: 190px;
  object-fit: cover;
  display: block;
  width: 100%;
}

.scene-content {
  padding: 20px;
  display: flex;
  flex-direction: column;
  flex: 1;
}

.scene-tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--color-ink-black);
  font-weight: 700;
  margin-bottom: 6px;
}

.scene-title {
  font-size: 1.08rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 8px;
}

.scene-desc {
  font-size: 0.86rem;
  color: var(--color-ink-annotation);
  line-height: 1.65;
}

/* ==========================================================================
   7. 演示：左边任务，右边结果
   ========================================================================== */
.demo-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
  background: var(--color-page-bg);
}

.demo-dual-box {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border: 2px solid var(--color-book-rule);
  box-shadow: 4px 4px 0px rgba(17, 17, 17, 0.8);
}

.demo-pane-task {
  padding: 28px;
  background: var(--color-page-card);
  border-right: 1px solid var(--color-book-rule);
}

.demo-pane-result {
  padding: 28px;
  background: var(--color-page-pure);
}

.demo-pane-head {
  font-size: 0.8rem;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--color-ink-black);
  margin-bottom: 10px;
  display: flex;
  justify-content: space-between;
}

.demo-pane-title {
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 12px;
}

.demo-pane-desc {
  font-size: 0.88rem;
  color: var(--color-ink-annotation);
  line-height: 1.7;
  margin-bottom: 16px;
}

.code-snippet-pre {
  background: var(--color-page-bg);
  border: 1px solid var(--color-book-crease);
  padding: 14px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.6;
  color: var(--color-ink-black);
  overflow-x: auto;
}

/* ==========================================================================
   8. 开发者：左边卖点，右边可切换的代码
   ========================================================================== */
.developer-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
}

.dev-split-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 36px;
}

.dev-left-pitch {
  padding-right: 12px;
}

.pitch-point-item {
  margin-bottom: 24px;
}

.pitch-title {
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 6px;
}

.pitch-desc {
  font-size: 0.88rem;
  color: var(--color-ink-annotation);
  line-height: 1.7;
}

.dev-right-code-box {
  border: 2px solid var(--color-book-rule);
  background: var(--color-page-pure);
  box-shadow: 4px 4px 0px rgba(17, 17, 17, 0.8);
}

.code-lang-tabs {
  display: flex;
  border-bottom: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
}

.tab-btn {
  padding: 10px 18px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--color-ink-prose);
  border-right: 1px solid var(--color-book-rule);
}

.tab-btn.active {
  background: var(--color-book-rule);
  color: #ffffff;
}

.code-body-pre {
  padding: 20px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.65;
  color: var(--color-ink-black);
  overflow-x: auto;
}

/* ==========================================================================
   9. 企业：3 列 × 2 行
   ========================================================================== */
.enterprise-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
  background: var(--color-page-bg);
}

.enterprise-grid-3x2 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.ent-card {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
  padding: 24px;
}

.ent-num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 8px;
}

.ent-title {
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 8px;
}

.ent-desc {
  font-size: 0.86rem;
  color: var(--color-ink-annotation);
  line-height: 1.7;
}

/* ==========================================================================
   10. 下载和帮助：各 5 列
   ========================================================================== */
.downloads-help-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
}

.five-col-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}

.five-col-card {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
  padding: 18px 14px;
  display: flex;
  flex-direction: column;
}

.five-col-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-ink-black);
  font-weight: 700;
  margin-bottom: 6px;
}

.five-col-title {
  font-size: 0.96rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 6px;
}

.five-col-desc {
  font-size: 0.8rem;
  color: var(--color-ink-annotation);
  line-height: 1.6;
}

/* ==========================================================================
   11. 问答：默认折叠，点开才看步骤
   ========================================================================== */
.faq-section {
  padding: 56px 0;
  border-bottom: 2px solid var(--color-book-rule);
  background: var(--color-page-bg);
}

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

.faq-details {
  border: 1px solid var(--color-book-rule);
  background: var(--color-page-card);
}

.faq-summary {
  padding: 18px 24px;
  font-size: 1.02rem;
  font-weight: 800;
  color: var(--color-ink-black);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.faq-toggle-icon {
  font-family: var(--font-mono);
  font-size: 1.2rem;
  color: var(--color-ink-black);
  transition: transform 0.2s ease;
}

.faq-details[open] .faq-toggle-icon {
  transform: rotate(45deg);
}

.faq-content-drawer {
  padding: 0 24px 22px;
  border-top: 1px dashed var(--color-book-crease);
  margin-top: 6px;
  padding-top: 16px;
}

.faq-step-line {
  font-size: 0.9rem;
  color: var(--color-ink-prose);
  line-height: 1.8;
  margin-bottom: 8px;
}

.faq-step-line strong {
  color: var(--color-ink-black);
}

/* ==========================================================================
   12. 页脚：品牌说明加四列链接
   ========================================================================== */
.site-footer {
  padding: 56px 0 32px;
  background: #eae6dc;
  border-top: 2px solid var(--color-book-rule);
}

.footer-top-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
  gap: 32px;
  margin-bottom: 40px;
}

.footer-brand-title {
  font-size: 1.2rem;
  font-weight: 900;
  color: var(--color-ink-black);
  margin-bottom: 12px;
}

.footer-brand-desc {
  font-size: 0.86rem;
  color: var(--color-ink-annotation);
  line-height: 1.8;
  padding-right: 18px;
}

.footer-col-title {
  font-size: 0.92rem;
  font-weight: 800;
  color: var(--color-ink-black);
  margin-bottom: 14px;
  border-bottom: 1px solid var(--color-book-crease);
  padding-bottom: 6px;
}

.footer-links-list {
  list-style: none;
}

.footer-links-list li {
  margin-bottom: 8px;
}

.footer-links-list a {
  font-size: 0.84rem;
  color: var(--color-ink-annotation);
}

.footer-links-list a:hover {
  color: var(--color-ink-black);
}

.footer-bottom-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--color-book-crease);
  padding-top: 20px;
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--color-ink-muted);
}

/* ==========================================================================
   响应式调整
   ========================================================================== */
@media (max-width: 1024px) {
  .cap-grid-4x2 {
    grid-template-columns: repeat(2, 1fr);
  }
  .five-col-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .metrics-4-col {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-top-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .nav-anchors {
    display: none;
  }
  .hero-h1 {
    font-size: 1.65rem;
  }
  .book-spine-layout-wrapper {
    grid-template-columns: 1fr;
  }
  .book-single-column-prose {
    border-right: none;
    border-bottom: 2px solid var(--color-book-rule);
    padding: 24px 18px;
  }
  .fore-edge-stain-gutter {
    flex-direction: row;
    min-height: 70px;
  }
  .edge-cut-segment {
    border-bottom: none;
    border-right: 1px solid rgba(255, 255, 255, 0.25);
    padding: 10px 4px;
  }
  .edge-cut-segment:last-child {
    border-right: none;
  }
  .edge-margin-note {
    font-size: 0.8rem;
  }
  .catalog-cards-3,
  .scenes-grid-3x2,
  .demo-dual-box,
  .dev-split-grid,
  .enterprise-grid-3x2 {
    grid-template-columns: 1fr;
  }
  .five-col-grid {
    grid-template-columns: 1fr;
  }
  .metrics-4-col {
    grid-template-columns: 1fr;
  }
  .footer-top-grid {
    grid-template-columns: 1fr;
  }
}