/* ============================================================
   CP — 一套开放的通讯标准
   深色为主 · 铜金点缀

   色板来源：assets/logo.png 逐像素采样
   对比度：全部经 WCAG 2.1 实测，注释中标注比值
   ============================================================ */

/* ------------------------------------------------------------
   1. 设计令牌
   ------------------------------------------------------------ */
:root {
  /* --- 基础色：深蓝，取自 logo 背景 --- */
  --navy-950: #050F2A;
  --navy-900: #06122F;
  --navy-800: #0A1B45;   /* logo 主底色 */
  --navy-700: #12295C;
  --navy-600: #17336E;
  --navy-500: #1E3E80;

  /* --- 基础色：铜金，取自 logo 字母 --- */
  --copper-800: #6C1818;  /* 字母暗部 */
  --copper-700: #8A3226;
  --copper-600: #A8483C;  /* 字母主体 */
  --copper-500: #C4594A;
  --copper-400: #E8A090;  /* 提亮铜 */
  --copper-300: #FCCCC0;  /* 字母高光 */
  --copper-200: #FFE8E0;

  /* --- 基础色：文字 --- */
  --warm-50: #F5EFE9;
  --slate-400: #A9B0C4;
  --slate-500: #6E7A99;

  /* --- 语义色 --- */
  --bg:            var(--navy-800);
  --bg-deep:       var(--navy-900);
  --bg-deeper:     var(--navy-950);
  --surface:       var(--navy-700);
  --surface-hi:    var(--navy-600);

  --text:          var(--warm-50);   /* 14.66:1 on --bg  AAA */
  --text-muted:    var(--slate-400); /*  7.72:1 on --bg  AA  */
  --text-dim:      var(--slate-500); /*  3.91:1 on --bg  仅大字号 */

  /* 铜金只用于填充与图形：在深底上仅 2.91:1，禁止作为文字色 */
  --accent:        var(--copper-600);
  --accent-hi:     var(--copper-500);
  --accent-deep:   var(--copper-800);
  --accent-text:   var(--copper-400); /* 7.85:1 on --bg  AA  */
  --accent-glow:   var(--copper-300); /* 11.58:1 on --bg AAA */

  --border:        rgba(252, 204, 192, 0.14);
  --border-strong: rgba(252, 204, 192, 0.28);

  /* --- 字体：全系统字体，零下载 --- */
  --font-sans: system-ui, -apple-system, 'Segoe UI', 'PingFang SC',
               'Hiragino Sans GB', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
  --font-mono: ui-monospace, 'Cascadia Mono', 'SF Mono', Consolas,
               'Liberation Mono', monospace;

  /* --- 尺寸 --- */
  --header-h: 4rem;
  --container: 1180px;
  --gutter: 1.25rem;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;

  --section-y: clamp(3.5rem, 8vw, 6.5rem);

  /* --- 动效 --- */
  --t-fast: 140ms ease;
  --t-base: 240ms ease;
}

@media (min-width: 768px) {
  :root {
    --header-h: 5rem;
    --gutter: 2rem;
  }
}

/* 窄屏收到 16px（可读性下限），给并排的下载列多让出 8px */
@media (max-width: 480px) {
  :root { --gutter: 1rem; }
}

/* ------------------------------------------------------------
   2. 重置与基础
   ------------------------------------------------------------ */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--text-muted);
  background-color: var(--bg);
  /* 顶部铜金光晕，避免大面积深蓝发闷 */
  background-image:
    radial-gradient(ellipse 90% 55% at 50% -10%, rgba(23, 51, 110, 0.85) 0%, transparent 62%),
    radial-gradient(ellipse 55% 40% at 88% 12%, rgba(168, 72, 60, 0.10) 0%, transparent 58%);
  background-repeat: no-repeat;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

/* 细颗粒噪点：消除深色大面积渐变的色带 */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='120' height='120' filter='url(%23n)'/%3E%3C/svg%3E");
}

main {
  flex: 1;
  position: relative;
  z-index: 1;
}

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

a {
  color: inherit;
  text-decoration: none;
}

ul { list-style: none; }

h1, h2, h3, h4 {
  color: var(--text);
  line-height: 1.22;
  text-wrap: balance;
  font-weight: 700;
}

code {
  font-family: var(--font-mono);
  font-size: 0.9em;
}

:focus-visible {
  outline: 2px solid var(--accent-glow);
  outline-offset: 3px;
  border-radius: 4px;
}

/* 锚点跳转时避开吸顶导航 */
[id] { scroll-margin-top: calc(var(--header-h) + 1.5rem); }

/* ------------------------------------------------------------
   3. 布局
   ------------------------------------------------------------ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  padding-block: var(--section-y);
  position: relative;
}

/* 交替底色，制造段落节奏 */
.section--tint {
  background: var(--bg-deep);
  border-block: 1px solid var(--border);
}

.section-head {
  max-width: 44rem;
  margin-bottom: clamp(2.25rem, 5vw, 3.5rem);
}

.section-head--center {
  max-width: 36rem;
  margin-inline: auto;
  text-align: center;
}

.section-head--center .section-desc { margin-inline: auto; }

.section-label {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent-text);
  margin-bottom: 0.9rem;
}

.section-title {
  font-size: clamp(1.5rem, 3.4vw, 2.15rem);
  letter-spacing: -0.02em;
  margin-bottom: 0.9rem;
}

.section-desc {
  color: var(--text-muted);
  font-size: 1.02rem;
  line-height: 1.75;
  max-width: 40rem;
}

/* ------------------------------------------------------------
   4. 按钮
   ------------------------------------------------------------ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  line-height: 1;
  letter-spacing: 0.01em;
  padding: 0.72rem 1.4rem;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  white-space: nowrap;
  transition: background var(--t-fast), border-color var(--t-fast),
              transform var(--t-fast), box-shadow var(--t-fast);
}

/* 铜金填充 + 白字：5.74:1  AA */
.btn-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 6px 20px rgba(168, 72, 60, 0.32);
}

.btn-primary:hover {
  background: var(--accent-hi);
  transform: translateY(-2px);
  box-shadow: 0 10px 28px rgba(168, 72, 60, 0.45);
}

.btn-ghost {
  background: rgba(252, 204, 192, 0.06);
  color: var(--accent-glow);
  border-color: var(--border);
}

.btn-ghost:hover {
  background: rgba(252, 204, 192, 0.12);
  border-color: var(--border-strong);
  transform: translateY(-2px);
}

.btn-lg {
  font-size: 1rem;
  padding: 0.95rem 1.9rem;
  border-radius: var(--radius-md);
}

/* 用 em：图标与间距随按钮字号缩放，窄屏下小按钮里不会撑出来 */
.btn svg {
  width: 1.1em;
  height: 1.1em;
  flex-shrink: 0;
}

/* ------------------------------------------------------------
   5. 头部导航
   ------------------------------------------------------------ */
.header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 50;
  background: rgba(10, 27, 69, 0.82);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  height: var(--header-h);
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 0.7rem;
  position: relative;
  z-index: 2;
}

.logo-link img {
  width: 2.1rem;
  height: 2.1rem;
  border-radius: 9px;
  box-shadow: 0 0 0 1px var(--border);
}

.logo-text {
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  color: var(--text);
}

.nav-desktop {
  display: none;
  align-items: center;
  gap: 0.15rem;
}

.nav-link {
  padding: 0.5rem 0.9rem;
  font-size: 0.88rem;
  color: var(--text-muted);
  border-radius: var(--radius-sm);
  transition: color var(--t-fast), background var(--t-fast);
}

.nav-link:hover {
  color: var(--accent-glow);
  background: rgba(252, 204, 192, 0.07);
}

.header-cta { display: none; }

@media (min-width: 900px) {
  .nav-desktop { display: flex; }
  .header-cta  { display: block; }
}

/* --- 移动端菜单（checkbox hack，零 JS）--- */
/* 用裁剪隐藏而非 display:none，保留键盘可聚焦；焦点环落到可见按钮上 */
.menu-toggle {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.menu-toggle:focus-visible ~ .container .menu-btn {
  outline: 2px solid var(--accent-glow);
  outline-offset: 2px;
}

.menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  color: var(--text-muted);
  cursor: pointer;
  border-radius: var(--radius-sm);
  position: relative;
  z-index: 2;
}

.menu-btn:hover { color: var(--accent-glow); }
.menu-btn svg { width: 1.5rem; height: 1.5rem; }

.menu-btn .icon-close { display: none; }
/* checkbox 是 header 的直接子元素，.container / .mobile-menu 才是它的兄弟 */
.menu-toggle:checked ~ .container .menu-btn .icon-burger { display: none; }
.menu-toggle:checked ~ .container .menu-btn .icon-close  { display: block; }

@media (min-width: 900px) {
  .menu-btn { display: none; }
}

.mobile-menu {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 40;
  background: rgba(6, 18, 47, 0.97);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.75rem;
  padding: 2rem var(--gutter);
}

.menu-toggle:checked ~ .mobile-menu { display: flex; }

.mobile-menu .nav-link {
  font-size: 1.2rem;
  color: var(--text);
}

/* ------------------------------------------------------------
   6. Hero
   ------------------------------------------------------------ */
.hero {
  position: relative;
  padding-block: calc(var(--header-h) + clamp(2.5rem, 7vw, 5rem)) clamp(3rem, 7vw, 5.5rem);
}

.hero-grid {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: clamp(2.5rem, 6vw, 4rem);
}

.hero-text { width: 100%; }

.hero-title {
  font-size: clamp(2rem, 6.2vw, 3.4rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.08;
  margin-bottom: 1.15rem;
}

.grad {
  background: linear-gradient(100deg, var(--accent-text) 0%, var(--accent-glow) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-desc {
  font-size: clamp(1rem, 2vw, 1.1rem);
  line-height: 1.75;
  max-width: 33rem;
  margin-bottom: 2rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.75rem;
}

.hero-visual {
  width: 100%;
  max-width: 20rem;
  flex-shrink: 0;
}

.topology {
  width: 100%;
  height: auto;
  display: block;
  animation: float 7s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50%      { transform: translateY(-10px); }
}

@media (min-width: 1000px) {
  .hero-grid {
    flex-direction: row;
    align-items: center;
  }
  .hero-text  { flex: 1 1 auto; }
  .hero-visual { flex: 0 0 24rem; max-width: 24rem; }
}

/* ------------------------------------------------------------
   7. 信任条
   ------------------------------------------------------------ */
.trust {
  background: var(--bg-deep);
  border-block: 1px solid var(--border);
  padding-block: clamp(1.5rem, 3vw, 2rem);
}

.trust-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem 2rem;
}

@media (min-width: 640px) {
  .trust-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (min-width: 1000px) {
  .trust-grid { grid-template-columns: repeat(4, 1fr); }
}

.trust-item {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
}

.trust-item svg {
  width: 1.15rem;
  height: 1.15rem;
  flex-shrink: 0;
  margin-top: 0.2rem;
  color: var(--accent-text);
}

.trust-item h3 {
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 0.15rem;
}

.trust-item p {
  font-size: 0.82rem;
  color: var(--text-dim);
  line-height: 1.55;
}

/* ------------------------------------------------------------
   8. 痛点
   ------------------------------------------------------------ */
.problem-list {
  display: flex;
  flex-direction: column;
}

.problem-item {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding-block: clamp(1.75rem, 4vw, 2.5rem);
  border-top: 1px solid var(--border);
}

.problem-item:last-child {
  border-bottom: 1px solid var(--border);
}

.problem-num {
  font-family: var(--font-mono);
  font-size: clamp(2.5rem, 7vw, 4rem);
  font-weight: 600;
  line-height: 1;
  color: transparent;
  -webkit-text-stroke: 1px rgba(252, 204, 192, 0.3);
  flex-shrink: 0;
}

.problem-body h3 {
  font-size: clamp(1.1rem, 2.4vw, 1.4rem);
  letter-spacing: -0.015em;
  margin-bottom: 0.5rem;
}

.problem-body p {
  font-size: 0.98rem;
  line-height: 1.75;
  max-width: 46rem;
}

@media (min-width: 768px) {
  .problem-item {
    flex-direction: row;
    align-items: baseline;
    gap: 2.5rem;
  }
  .problem-num { width: 5.5rem; }
}

/* ------------------------------------------------------------
   9. 产品特性 — Bento
   ------------------------------------------------------------ */
.bento {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

@media (min-width: 768px) {
  .bento { grid-template-columns: repeat(4, 1fr); }
  .bento-card--wide { grid-column: span 2; }
  .bento-card--full { grid-column: span 4; }
  .bento-card--tall { grid-column: span 2; grid-row: span 2; }
}

.bento-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: clamp(1.35rem, 3vw, 1.85rem);
  display: flex;
  flex-direction: column;
  transition: border-color var(--t-base), background var(--t-base), transform var(--t-base);
}

.bento-card:hover {
  border-color: var(--border-strong);
  background: var(--surface-hi);
  transform: translateY(-3px);
}

.bento-icon {
  width: 2.75rem;
  height: 2.75rem;
  border-radius: var(--radius-md);
  background: rgba(232, 160, 144, 0.12);
  border: 1px solid var(--border);
  display: grid;
  place-items: center;
  color: var(--accent-glow);
  margin-bottom: 1.15rem;
}

.bento-icon svg {
  width: 1.3rem;
  height: 1.3rem;
}

.bento-card h3 {
  font-size: 1.08rem;
  letter-spacing: -0.01em;
  margin-bottom: 0.5rem;
}

.bento-card p {
  font-size: 0.92rem;
  color: var(--text-dim);
  line-height: 1.68;
}

/* 主推卡片：铜金描边 + 微光 */
.bento-card--tall {
  background:
    linear-gradient(150deg, rgba(168, 72, 60, 0.16) 0%, transparent 55%),
    var(--surface);
  border-color: var(--border-strong);
}

.bento-card--tall p {
  font-size: 0.95rem;
  color: var(--text-muted);
}

/* 主推卡的落款清单：margin-top:auto 让它贴住卡片底部，
   填掉跨两行留下的空白，而不是让内容悬在上半截 */
.bento-list {
  margin-top: auto;
  padding-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-size: 0.86rem;
  color: var(--text-muted);
}

.bento-list li {
  display: flex;
  gap: 0.55rem;
  align-items: flex-start;
}

.bento-list li::before {
  content: '';
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--accent-text);
  margin-top: 0.55rem;
  flex-shrink: 0;
}

/* ------------------------------------------------------------
   10. 运作方式
   ------------------------------------------------------------ */
.steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

@media (min-width: 768px) {
  .steps { grid-template-columns: repeat(4, 1fr); gap: 1.5rem; }
}

.step {
  position: relative;
  padding-top: 0;
}

.step-num {
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--accent-glow);
  background: rgba(168, 72, 60, 0.18);
  border: 1px solid var(--border-strong);
  margin-bottom: 1.1rem;
  position: relative;
  z-index: 1;
}

/* 横向连接线（桌面） */
@media (min-width: 768px) {
  .step:not(:last-child)::after {
    content: '';
    position: absolute;
    top: 1.5rem;
    left: 3rem;
    width: calc(100% - 3rem + 1.5rem);
    height: 1px;
    background: linear-gradient(90deg, rgba(252, 204, 192, 0.42), rgba(252, 204, 192, 0.08));
  }
}

.step h3 {
  font-size: 1rem;
  margin-bottom: 0.45rem;
}

.step p {
  font-size: 0.88rem;
  color: var(--text-dim);
  line-height: 1.65;
}

/* ------------------------------------------------------------
   11. 下载
   ------------------------------------------------------------ */
/* 两列并排（含手机）：窄屏靠缩小手机模型适配，不给按钮留溢出风险 */
.download-grid {
  display: flex;
  justify-content: center;
  align-items: flex-start;
  gap: 1rem;
}

.download-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.9rem;
  text-align: center;
  min-width: 0;
  flex: 1 1 0;
}

@media (min-width: 768px) {
  .download-grid { gap: 4rem; }
  .download-item { flex: 0 1 auto; gap: 1.35rem; max-width: 18rem; }
}

/* 手机模型
   内部尺寸一律用 em，继承自 .device 的 font-size——
   改这一行就能整体缩放，不必逐个属性调 */
.device {
  position: relative;
  font-size: 1rem;
  width: 11em;
  height: 21.5em;
  flex-shrink: 0;
  border-radius: 1.75em;
  background: var(--navy-950);
  border: 1px solid var(--border-strong);
  padding: 0.6em 0.45em;
  box-shadow: 0 1.4em 3.5em rgba(0, 0, 0, 0.5), 0 0 0 1px rgba(0, 0, 0, 0.3);
}

.device::before {
  content: '';
  position: absolute;
  top: 0.55em;
  left: 50%;
  transform: translateX(-50%);
  width: 3em;
  height: 0.25em;
  border-radius: 0.2em;
  background: rgba(252, 204, 192, 0.18);
}

.device-screen {
  height: 100%;
  border-radius: 1.25em;
  background: linear-gradient(180deg, var(--navy-800) 0%, var(--navy-950) 100%);
  border: 1px solid var(--border);
  padding: 1.5em 0.65em 0.65em;
  display: flex;
  flex-direction: column;
  gap: 0.6em;
  overflow: hidden;
}

/* 模拟聊天 */
.chat {
  display: flex;
  gap: 0.35em;
  align-items: flex-end;
}

.chat--out { flex-direction: row-reverse; }

.chat-avatar {
  width: 1.1em;
  height: 1.1em;
  border-radius: 50%;
  flex-shrink: 0;
  background: var(--navy-500);
  border: 1px solid var(--border);
}

.chat--out .chat-avatar {
  background: var(--accent-deep);
  border-color: var(--border-strong);
}

.bubble {
  height: 0.55em;
  border-radius: 0.4em;
  background: var(--navy-600);
  flex-shrink: 0;
}

.chat--out .bubble { background: rgba(168, 72, 60, 0.65); }

.bubble--w70 { width: 70%; }
.bubble--w85 { width: 85%; }
.bubble--w50 { width: 50%; }
.bubble--w62 { width: 62%; }

/* 多行消息：真实聊天里气泡高度是参差的，一律等高会显得像骨架屏 */
.bubble--tall { height: 1.5em; }

.bubble--solo {
  margin-left: 1.45em;
}

.chat--out .bubble--solo {
  margin-left: 0;
  margin-right: 1.45em;
}

/* 设备背后的铜金光晕 */
.device-glow {
  position: absolute;
  inset: 18% -25% 12%;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(168, 72, 60, 0.35), transparent 68%);
  filter: blur(2.6em);
  z-index: -1;
  pointer-events: none;
}

.download-label {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text);
}

.download-note {
  font-size: 0.82rem;
  color: var(--text-dim);
  text-align: center;
  margin-top: 2.25rem;
}

/* 窄屏：整体缩小手机模型，按钮收紧以塞进半宽列 */
@media (max-width: 767px) {
  .device { font-size: 0.66rem; }
  .download-label { font-size: 0.88rem; }
  .download-note { margin-top: 1.75rem; }

  .download-item .btn {
    width: 100%;
    font-size: 0.75rem;
    padding: 0.62rem 0.7rem;
  }
}

@media (max-width: 380px) {
  .device { font-size: 0.6rem; }
  .download-item .btn { font-size: 0.7rem; padding: 0.55rem 0.45rem; }
}

/* ------------------------------------------------------------
   12. 数据条
   全站唯一的实证数字。放在下载之前，给转化点垫一层可信度
   ------------------------------------------------------------ */
.stats {
  background: var(--bg-deep);
  border-block: 1px solid var(--border);
  padding-block: clamp(1.75rem, 4vw, 2.5rem);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
  text-align: center;
}

.stat-num {
  font-family: var(--font-mono);
  font-size: clamp(1.4rem, 4.5vw, 2rem);
  font-weight: 600;
  color: var(--accent-glow);
  line-height: 1.15;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-top: 0.3rem;
}

/* ------------------------------------------------------------
   13. 结尾 CTA
   ------------------------------------------------------------ */
.cta {
  background:
    radial-gradient(ellipse 70% 120% at 50% 0%, rgba(196, 89, 74, 0.28) 0%, transparent 65%),
    linear-gradient(160deg, var(--copper-700) 0%, var(--copper-800) 55%, var(--navy-950) 100%);
  border-top: 1px solid var(--border-strong);
  padding-block: clamp(3.5rem, 8vw, 6rem);
  text-align: center;
}

.cta h2 {
  font-size: clamp(1.5rem, 4vw, 2.3rem);
  letter-spacing: -0.025em;
  margin-bottom: 0.85rem;
}

.cta p {
  color: rgba(245, 239, 233, 0.82); /* 5.9:1 on 铜金底 */
  font-size: 1.05rem;
  max-width: 34rem;
  margin: 0 auto 2rem;
}

.cta .hero-actions {
  justify-content: center;
  margin-bottom: 0;
}

/* CTA 区内的按钮反相，保证在铜金底上依然清晰 */
.cta .btn-primary {
  background: var(--warm-50);
  color: var(--copper-800);
  box-shadow: 0 8px 26px rgba(0, 0, 0, 0.32);
}

.cta .btn-primary:hover {
  background: #fff;
  color: var(--copper-800);
}

/* ------------------------------------------------------------
   14. 页脚
   ------------------------------------------------------------ */
.footer {
  background: var(--bg-deeper);
  border-top: 1px solid var(--border);
  padding-block: 2.25rem;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.1rem;
  text-align: center;
}

@media (min-width: 768px) {
  .footer-inner {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.footer-brand img {
  width: 1.6rem;
  height: 1.6rem;
  border-radius: 7px;
}

.footer-brand strong {
  color: var(--text);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.1em;
}

.footer-brand span {
  font-size: 0.8rem;
  color: var(--text-dim);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 0.5rem 1.1rem;
  font-size: 0.85rem;
}

.footer-links a {
  color: var(--text-muted);
  transition: color var(--t-fast);
}

.footer-links a:hover { color: var(--accent-glow); }

.footer-copy {
  font-size: 0.8rem;
  color: var(--text-dim);
}

/* ------------------------------------------------------------
   15. 错误页（404 / 502）— 与主站共用同一套令牌
   ------------------------------------------------------------ */
.error-page {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 3rem var(--gutter);
  text-align: center;
}

.error-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  max-width: 32rem;
}

.error-brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
}

.error-brand img {
  width: 2.5rem;
  height: 2.5rem;
  border-radius: 10px;
  box-shadow: 0 0 0 1px var(--border);
}

.error-brand span {
  font-size: 1.3rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  color: var(--text);
}

/* 用铜金渐变而非纯铜金：后者在深底上仅 2.91:1，不达大字号的 3:1 */
.error-code {
  font-family: var(--font-mono);
  font-size: clamp(4rem, 16vw, 7rem);
  font-weight: 600;
  line-height: 1;
  letter-spacing: 0.06em;
  background: linear-gradient(160deg, var(--accent-text) 0%, var(--accent-glow) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  filter: drop-shadow(0 0 34px rgba(168, 72, 60, 0.5));
}

.error-msg {
  margin-top: 1rem;
  margin-bottom: 2rem;
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.75;
}

/* ------------------------------------------------------------
   16. 工具类与无障碍
   ------------------------------------------------------------ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .topology { animation: none; }
}