/* ==========================================================================
   通义千问 - 扉页三态与书籍前三页设计系统 (Three-Pages Frontispiece Style)
   风格：书籍前三页 (Three-Pages Frontispiece)
   场景：品牌主视觉与前端组件调优
   核心规则：
   1. 布局：同一张画布分成封面、扉页、正文三个横条，从上到下变薄
   2. 风格说明：书籍前三页：纸色相同，只有字重在变
   3. 字体体系：封面特黑体 (Heavy Sans)，扉页楷体 (Kaiti)，正文宋体 (Songti)
   4. 内容约束：封面「千问」，扉页「qwen / qianwen」，正文第一句指向千问官网与千问网页版
   5. 视觉禁忌：严禁在画布内插入插图，纯粹凭借同一张纸上自上而下的厚薄收敛与字重梯度呈现书籍前奏
   ========================================================================== */

:root {
  /* 字体分层体系 */
  --font-heavy-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Arial Black", sans-serif;
  --font-kaiti: "Kaiti SC", "STKaiti", "KaiTi", "BiauKai", serif;
  --font-songti: "Songti SC", "Source Han Serif SC", "SimSun", "STSong", "Noto Serif SC", serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace;

  /* 统一纯净书纸用色（纸色相同，三页恒定） */
  --color-book-paper: #f8f6f0;        /* 统一书纸米白原色 */
  --color-book-paper-pure: #ffffff;   /* 亮面纸底 */
  --color-book-card: #f2efe7;         /* 衬纸淡阶 */
  --color-ink-primary: #151515;       /* 浓墨原色 */
  --color-ink-secondary: #2c2b29;     /* 墨色次阶 */
  --color-ink-subtle: #5a5752;        /* 铅墨说明 */
  --color-ink-muted: #8e8a82;         /* 极淡页码灰 */
  
  --color-thread-border: #151515;     /* 装订重切线 */
  --color-crease-line: #dcd7cb;       /* 折页细线 */
  --color-seal-cinnabar: #a62b2b;     /* 钤印朱砂红 */

  --container-max: 1220px;
}

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

body {
  background-color: var(--color-book-paper);
  color: var(--color-ink-secondary);
  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-primary);
  font-weight: 700;
  line-height: 1.35;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s ease, opacity 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(248, 246, 240, 0.98);
  backdrop-filter: blur(8px);
  border-bottom: 2px solid var(--color-thread-border);
}

.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-thread-border);
  background: var(--color-book-paper-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-primary);
  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-secondary);
  padding: 6px 2px;
  position: relative;
}

.nav-link:hover {
  color: var(--color-seal-cinnabar);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 1.5px;
  background: var(--color-seal-cinnabar);
  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-primary);
  border: 1px solid var(--color-crease-line);
  background: var(--color-book-paper-pure);
  font-weight: 600;
}

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

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

.btn-header-primary:hover {
  background: var(--color-seal-cinnabar);
  border-color: var(--color-seal-cinnabar);
}

/* ==========================================================================
   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-thread-border);
}

.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-crease-line);
  padding-bottom: 12px;
}

.hero-status-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--color-seal-cinnabar);
  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-primary);
  line-height: 1.32;
  letter-spacing: -0.02em;
}

.hero-desc {
  font-size: 1.08rem;
  color: var(--color-ink-subtle);
  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-thread-border);
  background: var(--color-book-paper-pure);
  box-shadow: 4px 4px 0px rgba(21, 21, 21, 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-primary);
  background: transparent;
}

.hero-search-btn {
  background: var(--color-thread-border);
  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: var(--color-seal-cinnabar);
}

/* ==========================================================================
   ★ 核心视觉风格：书籍前三页 · 扉页三态核心舞台 (Three-Pages Frontispiece)
   风格：书籍前三页
   场景：品牌主视觉
   布局：同一张画布分成封面、扉页、正文三个横条，从上到下变薄
   风格说明：书籍前三页：纸色相同，只有字重在变
   提示词：
   风格种「书籍前三页」。为通义千问做前三页的主视觉。布局：一张画布从上到下分成封面、扉页、正文三个横条，越往下越薄。风格：同一张纸，只靠字重区分三页。字体：封面特黑体，扉页楷体，正文宋体。封面「千问」，扉页 qwen / qianwen，正文第一句指向千问官网与千问网页版。不要插图。
   ========================================================================== */
.frontispiece-canvas-stage {
  /* 同一张纸底，纸色完全相同，绝对不换底色 */
  background: var(--color-book-paper);
  border: 2px solid var(--color-thread-border);
  padding: 0; /* 内部由三个横条平铺填充 */
  margin-top: 32px;
  box-shadow: 6px 6px 0px rgba(21, 21, 21, 0.85);
  position: relative;
  overflow: hidden;
}

/* 顶部刊刻标头 */
.frontispiece-head-ribbon {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 2px solid var(--color-thread-border);
  padding: 10px 24px;
  background: transparent;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: var(--color-ink-muted);
}

/* 核心布局：同一张画布从上到下分为封面、扉页、正文三个横条，越往下越薄 */

/* 1. 第一横条：封面 (Cover Page) - 最厚实（padding: 44px 36px），特黑体，特粗字重 */
.band-strip-cover {
  padding: 46px 36px; /* 最厚的一层 */
  border-bottom: 2px solid var(--color-thread-border);
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: transparent; /* 同一张纸色 */
}

.cover-meta-badge {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  color: var(--color-seal-cinnabar);
  margin-bottom: 12px;
}

/* 封面标题：特黑体，封面「千问」，字重超粗 900 */
.cover-title-heavy {
  font-family: var(--font-heavy-sans);
  font-weight: 900;
  font-size: 3.4rem;
  color: var(--color-ink-primary);
  line-height: 1.05;
  letter-spacing: 0.08em;
  margin-bottom: 10px;
}

.cover-sub-heavy {
  font-family: var(--font-heavy-sans);
  font-weight: 800;
  font-size: 1.15rem;
  color: var(--color-ink-secondary);
  letter-spacing: 0.02em;
}

/* 2. 第二横条：扉页 (Title Page) - 次厚（变薄，padding: 26px 36px），楷体，中等字重 */
.band-strip-titlepage {
  padding: 26px 36px; /* 明显变薄 */
  border-bottom: 1px dashed var(--color-thread-border);
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: transparent; /* 同一张纸色 */
}

.titlepage-meta-badge {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--color-ink-subtle);
  margin-bottom: 8px;
}

/* 扉页内容：楷体，字重中等 500/600，扉页「qwen / qianwen」 */
.titlepage-kaiti-content {
  font-family: var(--font-kaiti);
  font-weight: 600;
  font-size: 1.45rem;
  color: var(--color-ink-primary);
  line-height: 1.5;
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 18px;
}

.titlepage-kaiti-content .kw-latin {
  font-family: var(--font-kaiti);
  font-weight: 600;
  color: var(--color-seal-cinnabar);
  letter-spacing: 0.06em;
}

.titlepage-kaiti-content .kw-note {
  font-family: var(--font-kaiti);
  font-weight: 500;
  font-size: 1.08rem;
  color: var(--color-ink-subtle);
}

/* 3. 第三横条：正文 (Main Text) - 最薄（padding: 16px 36px），宋体，常规字重 400 */
.band-strip-prose {
  padding: 16px 36px; /* 极薄的一层 */
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: transparent; /* 同一张纸色 */
}

.prose-meta-badge {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
  margin-bottom: 6px;
}

/* 正文：宋体，常规字重 400，第一句明确指向千问官网与千问网页版 */
.prose-songti-firstline {
  font-family: var(--font-songti);
  font-weight: 400; /* 严格常规字重 */
  font-size: 0.98rem;
  line-height: 1.85;
  color: var(--color-ink-secondary);
  text-align: justify;
}

.prose-songti-firstline a {
  color: var(--color-seal-cinnabar);
  border-bottom: 1px solid var(--color-seal-cinnabar);
  font-weight: 600;
}

/* 底部收线 */
.frontispiece-foot-ribbon {
  border-top: 1px solid var(--color-crease-line);
  padding: 8px 24px;
  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-crease-line);
  background: var(--color-book-paper);
}

.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-crease-line);
}

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

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

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

.metric-card {
  border: 1px solid var(--color-thread-border);
  background: var(--color-book-card);
  padding: 24px 20px;
  box-shadow: 3px 3px 0px rgba(21, 21, 21, 0.6);
}

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

.metric-label {
  font-size: 0.88rem;
  color: var(--color-ink-subtle);
  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-thread-border);
}

.section-head-bar {
  margin-bottom: 36px;
  border-bottom: 2px solid var(--color-thread-border);
  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-seal-cinnabar);
  letter-spacing: 0.1em;
}

.section-h2 {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--color-ink-primary);
  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-thread-border);
  background: var(--color-book-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(21, 21, 21, 0.8);
}

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

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

.cap-line-1, .cap-line-2 {
  font-size: 0.85rem;
  color: var(--color-ink-subtle);
  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-thread-border);
  background: var(--color-book-paper);
}

.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-primary);
  margin-bottom: 18px;
  padding-left: 10px;
  border-left: 4px solid var(--color-seal-cinnabar);
  letter-spacing: 0.05em;
}

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

.catalog-card {
  border: 1px solid var(--color-thread-border);
  background: var(--color-book-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: #e6e2d8;
  color: var(--color-ink-primary);
  font-weight: 700;
  border: 1px solid var(--color-crease-line);
}

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

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

.card-desc {
  font-size: 0.88rem;
  color: var(--color-ink-subtle);
  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-thread-border);
  color: #ffffff;
  border: 1px solid var(--color-thread-border);
}

.btn-trial:hover {
  background: var(--color-seal-cinnabar);
  border-color: var(--color-seal-cinnabar);
}

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

.btn-doc:hover {
  background: var(--color-book-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-thread-border);
}

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

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

.scene-image-wrapper {
  width: 100%;
  height: 190px;
  overflow: hidden;
  background: #ece8df;
  border-bottom: 1px solid var(--color-thread-border);
}

.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-seal-cinnabar);
  font-weight: 700;
  margin-bottom: 6px;
}

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

.scene-desc {
  font-size: 0.86rem;
  color: var(--color-ink-subtle);
  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-thread-border);
  background: var(--color-book-paper);
}

.demo-dual-box {
  display: grid;
  grid-template-columns: 1fr 1fr;
  border: 2px solid var(--color-thread-border);
  box-shadow: 4px 4px 0px rgba(21, 21, 21, 0.8);
}

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

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

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

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

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

.code-snippet-pre {
  background: var(--color-book-paper);
  border: 1px solid var(--color-crease-line);
  padding: 14px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.6;
  color: var(--color-ink-primary);
  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-thread-border);
}

.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-primary);
  margin-bottom: 6px;
}

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

.dev-right-code-box {
  border: 2px solid var(--color-thread-border);
  background: var(--color-book-paper-pure);
  box-shadow: 4px 4px 0px rgba(21, 21, 21, 0.8);
}

.code-lang-tabs {
  display: flex;
  border-bottom: 1px solid var(--color-thread-border);
  background: var(--color-book-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-secondary);
  border-right: 1px solid var(--color-thread-border);
}

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

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

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

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

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

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

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

.ent-desc {
  font-size: 0.86rem;
  color: var(--color-ink-subtle);
  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-thread-border);
}

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

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

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

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

.five-col-desc {
  font-size: 0.8rem;
  color: var(--color-ink-subtle);
  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-thread-border);
  background: var(--color-book-paper);
}

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

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

.faq-summary {
  padding: 18px 24px;
  font-size: 1.02rem;
  font-weight: 800;
  color: var(--color-ink-primary);
  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-seal-cinnabar);
  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-crease-line);
  margin-top: 6px;
  padding-top: 16px;
}

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

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

/* ==========================================================================
   12. 页脚：品牌说明加四列链接
   ========================================================================== */
.site-footer {
  padding: 56px 0 32px;
  background: #ede9e0;
  border-top: 2px solid var(--color-thread-border);
}

.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-primary);
  margin-bottom: 12px;
}

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

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

.footer-links-list a:hover {
  color: var(--color-seal-cinnabar);
}

.footer-bottom-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--color-crease-line);
  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;
  }
  .cover-title-heavy {
    font-size: 2.4rem;
  }
  .band-strip-cover {
    padding: 30px 20px;
  }
  .band-strip-titlepage {
    padding: 20px 20px;
  }
  .band-strip-prose {
    padding: 14px 20px;
  }
  .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;
  }
}