/*
 * common.css — 银聆科技官网公共样式
 * 从 index.html 和 cases.html 中抽取的完全重复部分
 * 通过 <link rel="stylesheet" href="common.css"> 引入
 */

/* ═══════════════════════════════════════════
   :root — 品牌 Token
   ═══════════════════════════════════════════ */
:root {
  /* 品牌色 */
  --primary: #1B3A2D;
  --accent: #2E5E4E;
  --accent-blue: #2563EB;
  --accent-warm: #10B981;

  /* 背景色 */
  --bg: #FAFAF7;
  --bg-warm: #F4F3EF;
  --dark-bg: #0C1B2A;
  --tag-bg: #EDF5F1;

  /* 文字色 */
  --text: #1B3A2D;
  --text-secondary: #5A6B61;
  --text-muted: #6A7A70; /* 提升对比度至 4.5:1 以上 */
  --text-on-dark: rgba(255,255,255,0.6);
  --text-on-dark-strong: rgba(255,255,255,0.85);
  --white: #fff;

  /* 边框 */
  --border: #E2E5E3;
  --border-nav: #C8CDC9;
  --cross: #bbb;

  /* 圆角 token */
  --radius-xs: 2px;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-xl: 10px;
  --radius-pill: 20px;
  --radius-round: 50%;
  --radius: var(--radius-md);
  --bg-card: #fff;
  --ff-num: 'Futura', sans-serif;

  /* 字号 token */
  --text-xs: 11px;
  --text-sm: 12px;
  --text-base: 13px;
  --text-md: 14px;
  --text-lg: 15px;
  --text-xl: 16px;
  --text-2xl: 18px;
  --text-3xl: 20px;
  --text-4xl: 22px;
  --text-5xl: 28px;
  --text-6xl: 30px;
  --text-7xl: 48px;
  --fs-display: clamp(40px, 6vw, 72px);
  --fs-headline: clamp(32px, 4vw, 48px);
  --fs-title: clamp(24px, 3vw, 32px);
  --fs-section-title: clamp(24px, 3vw, 36px);

  /* 字重 token */
  --fw-light: 300;
  --fw-regular: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;
  --fw-extrabold: 800;
  --fw-black: 900;
}

/* ═══════════════════════════════════════════
   深色模式 Token
   ═══════════════════════════════════════════ */
[data-theme="dark"] {
  --primary: #A8C5B6;
  --accent: #5A9E84;
  --accent-warm: #34D399;

  --bg: #0B1410;
  --bg-warm: #131F1A;
  --dark-bg: #080E0B;
  --tag-bg: #1A2E24;
  --bg-card: #1E3228;

  --text: #D4E0DA;
  --text-secondary: #9AADA3;
  --text-muted: #7A8E82;
  --text-on-dark: rgba(255,255,255,0.5);
  --text-on-dark-strong: rgba(255,255,255,0.8);
  --white: #1A2E24;

  --border: #2A3E34;
  --border-nav: #1E3329;
  --cross: #4A5E54;
}

/* ═══════════════════════════════════════════
   基础 Reset
   ═══════════════════════════════════════════ */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }

body {
  font-family: 'Futura', 'TaipeiHei', -apple-system, "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* ═══════════════════════════════════════════
   @font-face — 渐进披露字体加载
   ═══════════════════════════════════════════ */

/* Futura — 英文+数字 */
@font-face {
  font-family: 'Futura';
  src: url('fonts/Futura.ttc') format('truetype-collection');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Futura';
  src: url('fonts/Futura.ttc') format('truetype-collection');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}

/* 台北黑体 — 按字符集分片 */
/* 片1: 基本拉丁 */
@font-face {
  font-family: 'TaipeiHei';
  src: url('fonts/TaipeiSans-Light.ttf') format('truetype');
  font-weight: 300;
  font-style: normal;
  font-display: swap;
  unicode-range: U+0000-00FF, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
  font-family: 'TaipeiHei';
  src: url('fonts/TaipeiSans-Regular.ttf') format('truetype');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  unicode-range: U+0000-00FF, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
  font-family: 'TaipeiHei';
  src: url('fonts/TaipeiSans-Bold.ttf') format('truetype');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
  unicode-range: U+0000-00FF, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
/* 片2: 中文常用字 */
@font-face {
  font-family: 'TaipeiHei';
  src: url('fonts/TaipeiSans-Light.ttf') format('truetype');
  font-weight: 300;
  font-style: normal;
  font-display: swap;
  unicode-range: U+4E00-9FFF, U+3400-4DBF, U+2F00-2FDF, U+3000-303F, U+FF00-FFEF;
}
@font-face {
  font-family: 'TaipeiHei';
  src: url('fonts/TaipeiSans-Regular.ttf') format('truetype');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  unicode-range: U+4E00-9FFF, U+3400-4DBF, U+2F00-2FDF, U+3000-303F, U+FF00-FFEF;
}
@font-face {
  font-family: 'TaipeiHei';
  src: url('fonts/TaipeiSans-Bold.ttf') format('truetype');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
  unicode-range: U+4E00-9FFF, U+3400-4DBF, U+2F00-2FDF, U+3000-303F, U+FF00-FFEF;
}

/* ═══════════════════════════════════════════
   导航栏 — 白底+底部线 → 滚动缩成悬浮毛玻璃
   ═══════════════════════════════════════════ */
.nav {
  position: sticky;
  top: 0;
  z-index: 500;
  background: var(--bg);
  border-bottom: 1px solid var(--border-nav);
  transition: top 0.15s ease-out,
              margin 0.15s ease-out,
              border-radius 0.15s ease-out,
              background 0.15s,
              border-color 0.15s,
              backdrop-filter 0.15s,
              box-shadow 0.15s;
}
.nav.scrolled {
  top: 10px;
  margin: 0 clamp(20px, 5vw, 80px);
  border-radius: var(--radius-xl);
  border-bottom: none;
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 8px rgba(0,0,0,0.08);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
  padding: 0 clamp(20px, 5vw, 80px);
}
.nav-logo {
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--primary);
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}
.nav-logo-svg {
  width: 25px;
  height: 36px;
  flex-shrink: 0;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 40px;
  list-style: none;
}
.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: var(--text-md);
  font-weight: var(--fw-medium);
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--primary); }
.nav-cta {
  background: var(--primary);
  color: var(--white) !important;
  padding: 6px 16px;
  border-radius: var(--radius-sm);
  font-size: var(--text-base);
  font-weight: var(--fw-semibold);
  opacity: 1 !important;
}

/* ── 深色模式导航栏 ── */
[data-theme="dark"] .nav { background: var(--bg); border-color: var(--border-nav); }
[data-theme="dark"] .nav.scrolled {
  background: rgba(15,26,20,0.85);
  box-shadow: 0 1px 8px rgba(0,0,0,0.3);
}
[data-theme="dark"] .nav-logo-svg {
  filter: brightness(0) saturate(100%) invert(75%) sepia(15%) saturate(300%) hue-rotate(100deg) brightness(90%) contrast(85%);
}

/* ── 主题切换按钮 ── */
.theme-toggle {
  width: 32px; height: 32px; border-radius: var(--radius-round);
  background: transparent; border: 1px solid var(--border);
  cursor: pointer; display: flex; align-items: center; justify-content: center;
  transition: all 0.3s; padding: 0; flex-shrink: 0;
}
.theme-toggle:hover { background: var(--bg-warm); }
.theme-toggle svg { width: 16px; height: 16px; color: var(--text-secondary); transition: color 0.3s; }
.theme-toggle:hover svg { color: var(--text); }
.theme-toggle .icon-sun, .theme-toggle .icon-moon { transition: opacity 0.2s; }
[data-theme="light"] .theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* ── 深色模式噪点覆盖层 ── */
[data-theme="dark"] body::after {
  content: '';
  position: fixed; inset: 0; z-index: 9999; pointer-events: none;
  opacity: 0.03;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.75' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
  mix-blend-mode: overlay;
}

/* ═══════════════════════════════════════════
   FOOTER — 四栏式布局
   ═══════════════════════════════════════════ */
.footer-new {
  background: var(--primary);
  color: var(--white);
  padding: 60px clamp(20px, 5vw, 80px) 0;
  position: relative;
  overflow: hidden;
}
.footer-new::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0.1;
  pointer-events: none;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='300' height='300'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='5' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='300' height='300' filter='url(%23n)'/%3E%3C/svg%3E");
}
.footer-columns {
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.5fr 1.5fr 1fr 2fr;
  gap: 40px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(255,255,255,0.12);
}
.footer-col-title { margin-bottom: 5px; }
.footer-col ul {
  list-style: none;
}
.footer-col ul li {
  margin-bottom: 10px;
}
.footer-col ul a {
  font-size: var(--text-md);
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  transition: color 0.2s;
}
.footer-col ul a:hover { color: var(--white); }
.footer-contact-item {
  font-size: var(--text-md);
  color: rgba(255,255,255,0.6);
  margin-bottom: 10px;
  line-height: 1.6;
}
.footer-contact-item a {
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  transition: color 0.2s;
}
.footer-contact-item a:hover { color: var(--white); }
.footer-social {
  display: flex;
  gap: 16px;
  margin-top: 16px;
}
.footer-social a {
  color: rgba(255,255,255,0.5);
  text-decoration: none;
  font-size: var(--text-base);
  transition: color 0.2s;
}
.footer-social a:hover { color: var(--white); }

/* 联系表单 */
.footer-form .form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}
.footer-form .form-group {
  margin-bottom: 16px;
}
.footer-form input,
.footer-form textarea {
  width: 100%;
  background: transparent;
  border: none;
  border-bottom: 1px solid rgba(255,255,255,0.25);
  color: var(--white);
  font-size: var(--text-md);
  padding: 8px 0;
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s;
}
.footer-form input::placeholder,
.footer-form textarea::placeholder {
  color: rgba(255,255,255,0.35);
}
.footer-form input:focus,
.footer-form textarea:focus {
  border-bottom-color: var(--accent-warm);
}
.footer-form textarea {
  resize: vertical;
  min-height: 60px;
}
.footer-form .form-note {
  font-size: var(--text-sm);
  color: rgba(255,255,255,0.35);
  margin-bottom: 12px;
}
.footer-form .form-submit {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: transparent;
  color: var(--white);
  border: 1px solid rgba(255,255,255,0.3);
  padding: 10px 24px;
  font-size: var(--text-base);
  font-weight: var(--fw-medium);
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
  letter-spacing: 0.5px;
}
.footer-form .form-submit:hover {
  background: rgba(255,255,255,0.08);
  border-color: rgba(255,255,255,0.5);
}
.footer-form .form-submit svg {
  width: 14px;
  height: 14px;
}
.form-success {
  font-size: var(--text-md);
  color: var(--accent-warm);
  padding: 12px 0;
}

/* 底部大图区 */
.footer-banner {
  max-width: 1200px;
  margin: 32px auto 24px;
  position: relative;
  z-index: 1;
  height: 260px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}
.footer-banner-bg {
  position: absolute;
  inset: 0;
  background: url('../images/footer-banner-bg.jpg') center/cover no-repeat;
  filter: brightness(0.7) saturate(0.85);
}
/* 噪点纹理 */
.footer-banner-noise {
  position: absolute;
  inset: 0;
  opacity: 0.35;
  pointer-events: none;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='300' height='300'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='5' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='300' height='300' filter='url(%23n)'/%3E%3C/svg%3E");
}
.footer-banner-content {
  position: relative;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}
.footer-banner-logo {
  width: 90px;
  height: auto;
  opacity: 0.9;
  filter: brightness(0) invert(1);
}
.footer-banner-slogan {
  font-size: var(--text-lg);
  color: rgba(255,255,255,0.85);
  letter-spacing: 1px;
  font-weight: var(--fw-semibold);
  font-family: 'TaipeiHei', -apple-system, "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  transform: translateY(-4px);
}

/* 法律声明 */
.footer-legal {
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
  padding: 16px 0 32px;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
}
.footer-legal p {
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.45); /* 提升对比度至 0.45+ */
  line-height: 1.6;
}

/* 备案信息 */
.footer-filing {
  text-align: right;
  flex-shrink: 0;
}
.footer-filing .filing-title {
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.55);
  margin-bottom: 4px;
}
.footer-filing .filing-links {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  margin-bottom: 4px;
}
.footer-filing .filing-badge {
  width: 20px;
  height: 20px;
  object-fit: contain;
  flex-shrink: 0;
}
.footer-filing .filing-item {
  font-size: var(--text-xs);
  color: rgba(255,255,255,0.55);
  text-decoration: none;
  transition: color 0.2s;
}
.footer-filing .filing-item:hover {
  color: rgba(255,255,255,0.85);
}
.footer-filing .filing-note {
  font-size: 10px;
  color: rgba(255,255,255,0.35);
}

/* ═══ 微信弹窗 ═══ */
.wechat-modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: rgba(0,0,0,0.15);
  align-items: center;
  justify-content: center;
}
.wechat-modal.show {
  display: flex;
}
.wechat-modal-box {
  background: rgba(255, 255, 255, 0.75);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: none;
  border-radius: var(--radius-xl);
  padding: 32px;
  text-align: center;
  max-width: 320px;
  width: 90%;
  position: relative;
  color: var(--text);
  box-shadow: 0 1px 8px rgba(0,0,0,0.08);
}
.wechat-modal-box h3 {
  font-size: var(--text-xl);
  color: var(--text);
  margin-bottom: 16px;
  font-weight: var(--fw-semibold);
}
.wechat-modal-qr {
  width: 180px;
  height: 180px;
  border-radius: var(--radius-lg);
  margin: 0 auto 16px;
  border: 1px solid var(--border);
}
.wechat-modal-box p {
  font-size: var(--text-base);
  color: var(--text-secondary);
}
.wechat-modal-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 28px;
  height: 28px;
  border: none;
  background: none;
  font-size: var(--text-2xl);
  color: var(--text-secondary);
  cursor: pointer;
  border-radius: var(--radius-round);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s;
}
.wechat-modal-close:hover { background: rgba(0,0,0,0.05); }

/* ═══ 通用按钮 ═══ */
.cta-btn {
  display: inline-block;
  background: var(--accent-warm);
  color: var(--white);
  padding: 14px 32px;
  border-radius: var(--radius-sm);
  font-size: var(--text-lg);
  font-weight: var(--fw-semibold);
  text-decoration: none;
  transition: opacity 0.2s;
}
.cta-btn:hover { opacity: 0.85; }

/* ═══ CTA 区域 ═══ */
.cta-section {
  padding: 132px clamp(20px, 5vw, 80px);
  background: var(--dark-bg);
  color: var(--white);
  position: relative;
  overflow: hidden;
  text-align: center;
}
.cta-section::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0.1;
  pointer-events: none;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='300' height='300'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='5' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='300' height='300' filter='url(%23n)'/%3E%3C/svg%3E");
}
.cta-inner {
  max-width: 700px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}
.cta-section h2 {
  font-size: clamp(28px, 3.5vw, 40px);
  font-weight: var(--fw-extrabold);
  margin-bottom: 16px;
  line-height: 1.2;
}
.cta-section p {
  font-size: var(--text-xl);
  color: rgba(255,255,255,0.6);
  margin-bottom: 32px;
  line-height: 1.7;
}

/* ═══════════════════════════════════════════
   FAQ 手风琴
   ═══════════════════════════════════════════ */
.faq-list {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.faq-item {
  background: var(--white);
  border-radius: var(--radius-xs);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: box-shadow 0.3s ease;
}
.faq-item:hover {
  box-shadow: 0 2px 12px rgba(0,0,0,0.04);
}
.faq-question {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 20px 24px;
  background: none;
  border: none;
  cursor: pointer;
  font-family: inherit;
  font-size: var(--text-lg);
  font-weight: var(--fw-medium);
  color: var(--text);
  text-align: left;
  line-height: 1.5;
  transition: color 0.2s;
}
.faq-question:hover {
  color: var(--accent);
}
.faq-icon {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: var(--radius-round);
  background: var(--tag-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  font-weight: var(--fw-light);
  color: var(--accent);
  transition: transform 0.4s cubic-bezier(0.16,1,0.3,1), background 0.3s, color 0.3s;
  line-height: 1;
}
.faq-item.open .faq-icon {
  transform: rotate(45deg);
  background: var(--accent);
  color: var(--white);
}
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s cubic-bezier(0.16,1,0.3,1);
}
.faq-item.open .faq-answer {
  max-height: 600px;
}
.faq-answer-inner {
  padding: 0 24px 24px;
  font-size: var(--text-md);
  color: var(--text-secondary);
  line-height: 1.8;
}
.faq-answer-inner p {
  margin-bottom: 10px;
}
.faq-answer-inner p:last-child {
  margin-bottom: 0;
}

/* ═══ 可访问性: focus-visible ═══ */
:focus-visible {
  outline: 2px solid var(--accent-blue);
  outline-offset: 2px;
}
a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent-blue);
  outline-offset: 2px;
}

/* ═══════════════════════════════════════════
   案例列表（index.html + cases.html 共用）
   ═══════════════════════════════════════════ */
.case-list {
  display: flex;
  flex-direction: column;
  position: relative;
  padding: 0;
  border: 1px solid var(--border);
}
.case-item {
  display: flex;
  align-items: center;
  gap: 48px;
  padding: 40px 16px;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
  color: inherit;
  transition: background 0.2s;
}
.case-item:last-child {
  border-bottom: none;
}
.case-item:hover {
  background: var(--bg-warm);
}
.case-images {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}
.case-img {
  width: 140px;
  height: 140px;
  border-radius: var(--radius-sm);
  background-size: cover;
  background-position: center;
  background-color: var(--bg-warm);
  position: relative;
  overflow: hidden;
}
.case-img::before {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.12'/%3E%3C/svg%3E");
  background-size: 128px 128px;
  opacity: 1;
  transition: opacity 0.6s cubic-bezier(0.16, 1, 0.3, 1);
  pointer-events: none;
  z-index: 1;
}
.case-img.img-loaded::before {
  opacity: 0;
}
.case-content {
  flex: 1;
}
.case-title {
  font-size: var(--text-3xl);
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
  text-transform: uppercase;
  letter-spacing: 0.02em;
  line-height: 1.3;
}
.case-desc {
  font-size: var(--text-md);
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 600px;
}
.case-arrow {
  flex-shrink: 0;
  color: var(--primary);
  transition: transform 0.2s;
  margin-left: -8px;
}
.case-item:hover .case-arrow {
  transform: translateX(8px);
}

/* ═══════════════════════════════════════════
   汉堡菜单按钮（桌面隐藏）
   ═══════════════════════════════════════════ */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 10px;
  background: none;
  border: none;
  cursor: pointer;
  z-index: 600;
}
.nav-toggle span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}
.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}
.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ═══════════════════════════════════════════
   移动端响应式 — 768px
   ═══════════════════════════════════════════ */
@media (max-width: 768px) {

  /* ── 导航栏 ── */
  .nav-toggle { display: flex; }
  .nav.scrolled { margin: 0; top: 0; border-radius: 0; }
  .nav-inner { padding: 0 16px; }
  .nav-links {
    display: none;
    position: fixed;
    inset: 0;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 0;
    background: var(--bg);
    z-index: 550;
    padding: 80px 24px 40px;
  }
  .nav-links.open {
    display: flex;
  }
  .nav-links li {
    width: 100%;
    text-align: center;
    padding: 14px 0;
    border-bottom: 1px solid var(--border);
  }
  .nav-links li:last-child { border-bottom: none; }
  .nav-links a {
    font-size: var(--text-xl);
    display: block;
    padding: 8px 0;
  }
  .nav-cta {
    margin-top: 12px;
    padding: 10px 24px !important;
    font-size: var(--text-lg) !important;
  }
  .theme-toggle { margin: 12px auto 0; }

  /* ── Nav logo ── */
  .nav-logo { white-space: nowrap; }
  .nav-logo-svg { width: 20px; height: 28px; }

  /* ── Footer ── */
  .footer-columns {
    grid-template-columns: 1fr;
    gap: 32px;
    padding-bottom: 32px;
    text-align: center;
  }
  .footer-col { text-align: center; }
  .footer-col ul { display: flex; flex-direction: column; align-items: center; }
  .footer-contact-item { text-align: center; }
  .footer-social { justify-content: center; }
  .footer-form { text-align: center; }
  .footer-form .form-row {
    grid-template-columns: 1fr;
  }
  .footer-form .form-group { text-align: center; }
  .footer-form input, .footer-form textarea { text-align: center; }
  .footer-form input::placeholder, .footer-form textarea::placeholder { text-align: center; }
  .footer-banner {
    height: auto;
    min-height: 160px;
    padding: 32px 16px;
    margin: 24px 0 16px;
  }
  .footer-banner-slogan { font-size: var(--text-md); }
  .footer-legal {
    flex-direction: column;
    gap: 8px;
    text-align: center;
    padding: 16px 0 24px;
  }
  .footer-filing { text-align: center; }
  .footer-filing .filing-links { justify-content: center; }

  /* ── 案例列表 ── */
  .case-item { padding: 24px 12px; gap: 12px; }
  .case-images { gap: 6px; }
  .case-img { width: 100px; height: 100px; }
  .case-title { font-size: var(--text-xl); }
  .case-desc { font-size: var(--text-base); }
  .case-arrow { display: none; }

  /* ── CTA ── */
  .cta-section { padding: 60px clamp(16px, 4vw, 40px); }

  /* ── FAQ ── */
  .faq-question {
    padding: 16px 18px;
    font-size: var(--text-base);
  }
  .faq-answer-inner {
    padding: 0 18px 18px;
    font-size: var(--text-sm);
  }

  /* ── 微信弹窗 ── */
  .wechat-modal-qr { width: 150px; height: 150px; }
}

/* ═══════════════════════════════════════════
   移动端响应式 — 480px
   ═══════════════════════════════════════════ */
@media (max-width: 480px) {
  .case-item { padding: 20px 10px; }
  .case-img { width: 80px; height: 80px; }
  .wechat-modal-qr { width: 130px; height: 130px; }
}

/* ═══════════════════════════════════════════
   深色模式 — 共享覆盖样式（从 index.html / cases.html 合并）
   ═══════════════════════════════════════════ */

/* CTA 区域 */
[data-theme="dark"] .cta-section { background: var(--dark-bg); }
[data-theme="dark"] .cta-section h2 { color: var(--text); }
[data-theme="dark"] .cta-section p { color: var(--text-secondary); }

/* Footer */
[data-theme="dark"] .footer-new { background: #0A1210; color: #fff; }
[data-theme="dark"] .footer-col-title { color: #fff; }
[data-theme="dark"] .footer-col h4 { color: #fff; }
[data-theme="dark"] .footer-col a { color: rgba(255,255,255,0.6); }
[data-theme="dark"] .footer-col a:hover { color: #fff; }
[data-theme="dark"] .footer-contact-item { color: rgba(255,255,255,0.6); }
[data-theme="dark"] .footer-contact-item a { color: rgba(255,255,255,0.6); }
[data-theme="dark"] .footer-form .form-submit { color: #fff; border-color: rgba(255,255,255,0.3); }
[data-theme="dark"] .footer-form input, [data-theme="dark"] .footer-form textarea { color: #fff; border-color: rgba(255,255,255,0.15); }
[data-theme="dark"] .footer-form input::placeholder, [data-theme="dark"] .footer-form textarea::placeholder { color: rgba(255,255,255,0.35); }
[data-theme="dark"] .footer-form .form-note { color: rgba(255,255,255,0.35); }
[data-theme="dark"] .footer-banner-bg { filter: brightness(0.4) saturate(0.7); }
[data-theme="dark"] .footer-legal { color: var(--text-muted); }

/* FAQ */
[data-theme="dark"] .faq-item {
  background: var(--bg-card);
  border-color: var(--border);
}
[data-theme="dark"] .faq-question {
  color: var(--text);
}
[data-theme="dark"] .faq-question:hover {
  color: var(--accent-warm);
}
[data-theme="dark"] .faq-icon {
  background: var(--tag-bg);
  color: var(--accent-warm);
}
[data-theme="dark"] .faq-item.open .faq-icon {
  background: var(--accent-warm);
  color: var(--white);
}

/* 表单 */
[data-theme="dark"] input, [data-theme="dark"] textarea {
  background: var(--bg-card); color: var(--text); border-color: var(--border);
}
[data-theme="dark"] .footer-form input, [data-theme="dark"] .footer-form textarea {
  background: transparent !important;
}
[data-theme="dark"] input::placeholder, [data-theme="dark"] textarea::placeholder {
  color: var(--text-muted);
}

/* 微信弹窗 */
[data-theme="dark"] .wechat-modal-box { background: var(--bg-card); }
[data-theme="dark"] .wechat-modal-box p { color: var(--text); }

/* 案例卡片 */
[data-theme="dark"] .case-item { background: var(--bg-card); border-color: var(--border); }
[data-theme="dark"] .case-title { color: var(--text); }
[data-theme="dark"] .case-desc { color: var(--text-secondary); }

/* Link Underline Animation */
.nav-link, .footer-link,
.nav-links a, .footer-links a {
  position: relative;
  display: inline-block;
}
.nav-link::before, .footer-link::before,
.nav-links a::before, .footer-links a::before {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 1px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform 0.4s cubic-bezier(0.625, 0.05, 0, 1);
}
.nav-link:hover::before, .footer-link:hover::before,
.nav-links a:hover::before, .footer-links a:hover::before {
  transform: scaleX(1);
  transform-origin: left;
}

/* ═══════════════════════════════════════════
   动画降级 — prefers-reduced-motion
   ═══════════════════════════════════════════ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .hero-video { display: none; }
  .hero-poster { display: block !important; }
}