/* ============================================
   宁乡智搜 - 设计系统重构
   宁乡蓝 + 暖木色 / 流体排版 / CSS Grid / 暗色模式
   ============================================ */

/* ============================================
   @layer base — CSS 变量、Reset、基础排版
   ============================================ */
@layer base {

  /* ---------- CSS 变量系统 ---------- */
  :root {
    /* 品牌色：宁乡蓝 + 暖木色 */
    --brand-50:  oklch(96% 0.04 245);
    --brand-100: oklch(92% 0.08 245);
    --brand-200: oklch(84% 0.12 245);
    --brand-300: oklch(74% 0.15 245);
    --brand-400: oklch(66% 0.17 245);
    --brand-500: oklch(60% 0.18 245);
    --brand-600: oklch(52% 0.16 245);
    --brand-700: oklch(44% 0.14 245);
    --brand-800: oklch(36% 0.12 245);
    --brand-900: oklch(28% 0.10 245);

    --warm-50:  oklch(97% 0.03 80);
    --warm-100: oklch(93% 0.05 80);
    --warm-200: oklch(87% 0.07 80);
    --warm-300: oklch(78% 0.08 80);
    --warm-400: oklch(68% 0.07 80);
    --warm-500: oklch(60% 0.06 80);

    /* 保持原前缀：--primary-*（映射到宁乡蓝） */
    --primary-50:  oklch(96% 0.04 245);
    --primary-100: oklch(92% 0.08 245);
    --primary-200: oklch(84% 0.12 245);
    --primary-300: oklch(74% 0.15 245);
    --primary-400: oklch(66% 0.17 245);
    --primary-500: oklch(60% 0.18 245);
    --primary-600: oklch(52% 0.16 245);
    --primary-700: oklch(44% 0.14 245);
    --primary-800: oklch(36% 0.12 245);
    --primary-900: oklch(28% 0.10 245);

    /* 中性色：微调向品牌蓝 (tinted neutrals) */
    --neutral-50:  oklch(98% 0.01 245);
    --neutral-100: oklch(94% 0.012 245);
    --neutral-200: oklch(88% 0.014 245);
    --neutral-300: oklch(78% 0.015 245);
    --neutral-400: oklch(60% 0.016 245);
    --neutral-500: oklch(48% 0.017 245);
    --neutral-600: oklch(40% 0.018 245);
    --neutral-700: oklch(32% 0.019 245);
    --neutral-800: oklch(24% 0.02 245);
    --neutral-900: oklch(18% 0.02 245);

    /* 功能色 */
    --rose-500:  oklch(55% 0.22 15);
    --rose-600:  oklch(48% 0.20 15);
    --emerald-500: oklch(58% 0.16 160);
    --emerald-600: oklch(50% 0.14 160);
    --green-600: oklch(52% 0.16 145);
    --green-700: oklch(44% 0.14 145);

    /* 表面色 (light-dark 暗色模式基础) */
    --surface-0:  light-dark(oklch(100% 0 0), oklch(22% 0.01 245));
    --surface-50: light-dark(oklch(98% 0.01 245), oklch(26% 0.015 245));
    --surface-100: light-dark(oklch(94% 0.012 245), oklch(30% 0.015 245));

    /* 间距 */
    --section-padding: clamp(20px, 5vw, 40px);
    --element-gap:   10px;
    --card-padding:  14px;

    /* 圆角 — 4px 步进 */
    --radius-sm:   4px;
    --radius-md:   8px;
    --radius-lg:   12px;
    --radius-xl:   16px;
    --radius-2xl:  24px;
    --radius-full: 9999px;

    /* 阴影 — 多层柔和，无纯黑 */
    --shadow-sm: 0 1px 2px oklch(0% 0 0 / 0.04), 0 1px 3px oklch(0% 0 0 / 0.06);
    --shadow-md: 0 4px 6px oklch(0% 0 0 / 0.04), 0 2px 4px oklch(0% 0 0 / 0.06);
    --shadow-lg: 0 12px 24px oklch(0% 0 0 / 0.06), 0 4px 8px oklch(0% 0 0 / 0.04);
    --shadow-xl: 0 20px 40px oklch(0% 0 0 / 0.08), 0 8px 16px oklch(0% 0 0 / 0.04);

    /* 排版 */
    --font-heading: "LXGW WenKai", "霞鹜文楷", "Noto Serif SC", serif;
    --font-body:    "Inter", "PingFang SC", "Microsoft YaHei", sans-serif;

    /* 过渡 */
    --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
    --transition-base: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  }

  /* ---------- Reset & Base ---------- */
  *,
  *::before,
  *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }

  html {
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
    scroll-behavior: smooth;
    color-scheme: light dark;
  }

  body {
    font-family: var(--font-body);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background: var(--surface-50);
    color: var(--neutral-900);
    font-size: clamp(0.95rem, 1.5vw, 1.1rem);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-overflow-scrolling: touch;
    padding-bottom: 36px;
  }

  h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    line-height: 1.2;
    font-weight: 700;
  }

  h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
  h2 { font-size: clamp(1.5rem, 3vw, 2.2rem); }
  h3 { font-size: clamp(1.2rem, 2vw, 1.6rem); }

  a {
    text-decoration: none;
    transition: color var(--transition-base);
    -webkit-tap-highlight-color: transparent;
    color: var(--primary-600);
  }

  a:hover { color: var(--primary-700); }

  button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
    -webkit-tap-highlight-color: transparent;
  }

  img,
  video,
  table,
  iframe {
    max-width: 100%;
    height: auto;
  }

  img[loading="lazy"] { opacity: 0; transition: opacity 0.3s ease; }
  img[loading="lazy"].loaded,
  img:not([loading]) { opacity: 1; }

  /* ---------- 触摸目标 ---------- */
  a, button, .btn, [role="button"] {
    min-height: 44px;
    min-width: 44px;
    touch-action: manipulation;
  }
  input, textarea, select { font-size: 16px; }

  /* ---------- 全局 focus-visible 光环 ---------- */
  :focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
    border-radius: var(--radius-sm);
  }

  /* ---------- 选择文本 ---------- */
  ::selection {
    background: var(--primary-200);
    color: var(--primary-900);
  }
}

/* ============================================
   @layer components — 动画、按钮、卡片、布局组件
   ============================================ */
@layer components {

  /* ---------- 顶部导航栏 ---------- */
  .top-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--surface-0);
    border-bottom: 1px solid var(--neutral-200);
    box-shadow: var(--shadow-sm);
  }
  .top-nav-inner {
    max-width: 640px;
    margin: 0 auto;
    padding: 0 16px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 48px;
  }
  .top-nav-back {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 14px;
    font-weight: 500;
    color: var(--neutral-700);
    text-decoration: none;
    transition: color 0.2s ease;
    min-height: 44px;
    min-width: 44px;
  }
  .top-nav-back:hover { color: var(--brand-500); }
  .top-nav-back svg { width: 18px; height: 18px; flex-shrink: 0; }
  .top-nav-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--neutral-900);
    margin: 0;
  }
  .top-nav-contact {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 6px 14px;
    border-radius: var(--radius-full);
    font-size: 13px;
    font-weight: 600;
    color: var(--brand-600);
    background: var(--brand-50);
    text-decoration: none;
    transition: all 0.2s ease;
    min-height: 36px;
  }
  .top-nav-contact:hover { background: var(--brand-100); }
  .top-nav-contact svg { width: 16px; height: 16px; flex-shrink: 0; }

  /* ---------- 动画 ---------- */
  @keyframes fadeInUp {
    from { opacity: 0; transform: translateY(24px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  @keyframes fadeInScale {
    from { opacity: 0; transform: scale(0.92); }
    to   { opacity: 1; transform: scale(1); }
  }

  @keyframes navBadgeGlow {
    0%, 100% {
      box-shadow: 0 0 0 1.5px oklch(60% 0.18 245 / 0.35), 0 0 8px oklch(60% 0.18 245 / 0.25);
      background: var(--primary-500);
    }
    50% {
      box-shadow: 0 0 0 2px oklch(60% 0.18 245 / 0.20), 0 0 14px oklch(60% 0.18 245 / 0.40);
      background: var(--primary-400);
    }
  }

  @media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
      animation-duration: 0.01ms !important;
      animation-iteration-count: 1 !important;
      transition-duration: 0.01ms !important;
      scroll-behavior: auto;
    }
  }

  /* ---------- Hero Section：非对称 + 几何装饰 ---------- */
  .hero-section {
    padding: 28px 16px 24px;
    background: var(--surface-0);
    position: relative;
    overflow: hidden;
    display: grid;
    place-items: center;
  }

  /* 宁乡装饰：淡色菱形/三角形几何图案 */
  .hero-section::before {
    content: '';
    position: absolute;
    top: -60px;
    right: -40px;
    width: 280px;
    height: 280px;
    background: oklch(60% 0.18 245 / 0.04);
    clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);
    pointer-events: none;
    animation: fadeInScale 1s var(--ease-out-expo) both;
  }

  .hero-section::after {
    content: '';
    position: absolute;
    bottom: -30px;
    left: -20px;
    width: 140px;
    height: 140px;
    background: oklch(75% 0.08 80 / 0.06);
    clip-path: polygon(50% 0%, 100% 100%, 0% 100%);
    pointer-events: none;
    animation: fadeInScale 1s var(--ease-out-expo) 0.2s both;
  }

  .container {
    max-width: 640px;
    margin: 0 auto;
    padding: 0 24px;
    position: relative;
    z-index: 1;
  }

  /* ---------- Logo Badge ---------- */
  .logo-badge {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 16px;
    animation: fadeInUp 0.6s var(--ease-out-expo) both;
  }

  .logo-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
  }

  .logo-icon img {
    width: 100%;
    height: 100%;
    object-fit: cover;
  }

  .logo-text {
    display: flex;
    flex-direction: column;
    gap: 4px;
  }

  .logo-title {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: clamp(0.9rem, 1.5vw, 1rem);
    font-weight: 600;
    color: var(--primary-600);
    font-family: var(--font-heading);
  }

  .logo-subtitle {
    font-size: clamp(0.75rem, 1vw, 0.82rem);
    color: var(--neutral-400);
  }

  /* ---------- Hero Typography ---------- */
  .hero-title {
    font-family: var(--font-heading);
    font-size: clamp(1.6rem, 4vw, 2.4rem);
    font-weight: 900;
    color: var(--neutral-900);
    margin-bottom: 8px;
    line-height: 1.1;
    letter-spacing: -0.03em;
    white-space: nowrap;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.1s both;
  }

  .hero-subtitle {
    font-size: clamp(0.95rem, 1.5vw, 1.15rem);
    color: var(--neutral-600);
    margin-bottom: 16px;
    line-height: 1.7;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.2s both;
    max-width: 640px;
    white-space: nowrap;
    text-align: center;
  }

  .hero-highlight {
    max-width: 640px;
    margin: 0 auto 24px;
  }

  .highlight-text {
    font-size: clamp(0.8rem, 1.1vw, 0.95rem);
    font-weight: 600;
    line-height: 1.7;
    color: var(--primary-700);
    background: var(--primary-50);
    border-radius: var(--radius-md);
    padding: 10px 16px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.3s both;
    box-shadow: var(--shadow-sm);
    word-break: break-word;
    text-align: center;
    display: block;
  }

  /* ---------- Platform Row ---------- */
  .platform-row {
    margin-bottom: 16px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.8s both;
  }

  .platform-label {
    font-size: clamp(0.7rem, 1vw, 0.8rem);
    color: var(--neutral-400);
    margin-bottom: 12px;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-weight: 600;
  }

  .platform-list {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
  }

  .platform-item {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: clamp(0.75rem, 1vw, 0.82rem);
    color: var(--neutral-500);
    font-weight: 500;
  }

  .platform-item img {
    width: 20px;
    height: 20px;
    border-radius: var(--radius-sm);
  }

  /* ---------- Card Grid：CSS Grid 替代 Flexbox ---------- */
  .card-grid {
    display: grid;
    grid-template-columns: 30% 1fr;
    gap: 12px;
    margin-bottom: 16px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.4s both;
    align-items: stretch;
  }

  .card-col-a {
    display: flex;
  }
  .card-col-b {
    display: flex;
  }

  .card-a {
    background: var(--surface-0);
    border-radius: var(--radius-lg);
    padding: 16px 12px;
    text-align: center;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--neutral-200);
    display: grid;
    place-items: center;
    align-content: center;
    gap: 12px;
    min-height: 100px;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    will-change: transform, box-shadow;
    width: 100%;
    height: 100%;
  }

  .card-a:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    border-color: var(--brand-200);
  }

  .card-a:active {
    transform: scale(0.97);
  }

  .card-a:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .card-a-icon {
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--rose-500);
  }

  .card-a-icon svg {
    width: 28px;
    height: 28px;
  }

  .card-a-text {
    font-size: 13px;
    font-weight: 600;
    color: var(--neutral-800);
    line-height: 1.5;
  }

  .card-b {
    background: var(--surface-0);
    border-radius: var(--radius-lg);
    padding: 16px 16px;
    display: grid;
    place-items: center;
    text-align: center;
    min-height: 100px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--neutral-200);
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    will-change: transform, box-shadow;
    width: 100%;
    height: 100%;
  }

  .card-b:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    border-color: var(--brand-200);
  }

  .card-b:active {
    transform: scale(0.97);
  }

  .card-b:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .card-b-title {
    font-size: 14px;
    font-weight: 500;
    color: var(--neutral-700);
    line-height: 1.6;
    margin-bottom: 8px;
  }

  .card-b-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    background: var(--primary-50);
    border: 1px solid var(--primary-200);
    border-radius: var(--radius-full);
    font-size: 12px;
    font-weight: 600;
    color: var(--primary-700);
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  }

  .card-b-btn:hover {
    background: var(--primary-100);
    color: var(--primary-800);
  }

  .card-b-btn:active {
    transform: scale(0.97);
  }

  .card-b-btn:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .card-b-hint {
    font-size: 11px;
    color: var(--neutral-400);
    margin-top: 6px;
  }

  /* ---------- 按钮系统 ---------- */
  .btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: var(--radius-full);
    font-size: 13px;
    font-weight: 600;
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
    text-decoration: none;
    line-height: 1.4;
    min-height: 44px;
  }

  .btn:active {
    transform: scale(0.97);
  }

  .btn:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .btn:disabled,
  .btn[aria-disabled="true"] {
    opacity: 0.45;
    pointer-events: none;
    cursor: not-allowed;
  }

  /* Primary */
  .btn-primary {
    background: var(--primary-600);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    box-shadow: 0 2px 4px oklch(0% 0 0 / 0.08), 0 4px 12px oklch(52% 0.16 245 / 0.25);
  }
  .btn-primary:hover {
    background: var(--primary-700);
    box-shadow: 0 4px 8px oklch(0% 0 0 / 0.10), 0 8px 24px oklch(44% 0.14 245 / 0.30);
    transform: translateY(-2px);
  }
  .btn-primary:active {
    transform: scale(0.97);
    box-shadow: var(--shadow-md);
  }

  /* Rose */
  .btn-rose {
    background: var(--rose-500);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    box-shadow: 0 2px 4px oklch(0% 0 0 / 0.08), 0 4px 12px oklch(55% 0.22 15 / 0.25);
  }
  .btn-rose:hover {
    background: var(--rose-600);
    box-shadow: 0 4px 8px oklch(0% 0 0 / 0.10), 0 8px 24px oklch(48% 0.20 15 / 0.30);
    transform: translateY(-2px);
  }
  .btn-rose:active {
    transform: scale(0.97);
    box-shadow: var(--shadow-md);
  }

  /* Emerald */
  .btn-emerald {
    background: var(--emerald-500);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    box-shadow: 0 2px 4px oklch(0% 0 0 / 0.08), 0 4px 12px oklch(58% 0.16 160 / 0.25);
  }
  .btn-emerald:hover {
    background: var(--emerald-600);
    box-shadow: 0 4px 8px oklch(0% 0 0 / 0.10), 0 8px 24px oklch(50% 0.14 160 / 0.30);
    transform: translateY(-2px);
  }
  .btn-emerald:active {
    transform: scale(0.97);
    box-shadow: var(--shadow-md);
  }

  /* Dark */
  .btn-dark {
    background: var(--neutral-800);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    box-shadow: 0 2px 4px oklch(0% 0 0 / 0.08), 0 4px 12px oklch(0% 0 0 / 0.15);
  }
  .btn-dark:hover {
    background: var(--neutral-900);
    box-shadow: 0 4px 8px oklch(0% 0 0 / 0.10), 0 8px 24px oklch(0% 0 0 / 0.20);
    transform: translateY(-2px);
  }
  .btn-dark:active {
    transform: scale(0.97);
    box-shadow: var(--shadow-md);
  }

  /* Outline */
  .btn-outline {
    background: var(--surface-0);
    color: var(--neutral-700);
    box-shadow: var(--shadow-sm);
  }
  .btn-outline:hover {
    box-shadow: var(--shadow-md);
    color: var(--primary-600);
  }
  .btn-outline:active {
    transform: scale(0.97);
  }

  /* ---------- Free Section ---------- */
  .free-section {
    margin-bottom: 20px;
  }

  .free-card {
    background: linear-gradient(135deg, var(--brand-50), oklch(98% 0.03 245));
    border: 1px solid var(--brand-100);
    border-radius: var(--radius-2xl);
    padding: var(--card-padding);
    text-align: center;
    box-shadow: var(--shadow-md);
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.5s both;
    will-change: transform, box-shadow;
  }

  .section-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-bottom: 8px;
  }

  .section-title {
    font-family: var(--font-heading);
    font-size: clamp(1rem, 2vw, 1.3rem);
    font-weight: 700;
    color: var(--neutral-900);
  }

  .free-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 12px;
    background: var(--rose-500);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    border-radius: var(--radius-full);
    font-size: clamp(0.7rem, 1vw, 0.8rem);
    font-weight: 700;
  }

  .section-desc {
    font-size: clamp(0.85rem, 1.2vw, 0.95rem);
    color: var(--neutral-600);
    margin-bottom: 16px;
    line-height: 1.7;
  }

  .btn-group {
    display: flex;
    flex-direction: column;
    gap: 12px;
    align-items: center;
  }

  /* ---------- Hosting Section ---------- */
  .hosting-section {
    margin-bottom: 20px;
  }

  .hosting-card {
    background: linear-gradient(135deg, oklch(97% 0.04 85), oklch(99% 0.02 80));
    border: 1px solid var(--warm-200);
    border-radius: var(--radius-2xl);
    padding: var(--card-padding);
    text-align: center;
    box-shadow: var(--shadow-md);
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.6s both;
    will-change: transform, box-shadow;
  }

  .hosting-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 14px;
    background: oklch(60% 0.08 80);
    color: #fff;
    border-radius: var(--radius-full);
    font-size: clamp(0.7rem, 1vw, 0.8rem);
    font-weight: 700;
  }

  /* ---------- Urgency Banner ---------- */
  .urgency-banner {
    background: var(--surface-50);
    border-radius: var(--radius-lg);
    padding: 10px 14px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 12px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.05s both;
    box-shadow: var(--shadow-sm);
  }

  .urgency-icon { font-size: 24px; flex-shrink: 0; }

  .urgency-text {
    font-size: clamp(0.8rem, 1vw, 0.88rem);
    color: var(--neutral-700);
    font-weight: 500;
    line-height: 1.6;
  }

  .urgency-text strong {
    color: var(--rose-500);
    font-weight: 700;
  }

  /* ---------- Case Section ---------- */
  .case-section {
    margin-bottom: 20px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.65s both;
  }

  .case-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px;
  }

  .case-header-icon { font-size: 20px; }

  .case-title {
    font-family: var(--font-heading);
    font-size: clamp(1.2rem, 2vw, 1.5rem);
    font-weight: 700;
    color: var(--neutral-900);
  }

  .case-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
  }

  .case-card {
    background: var(--surface-0);
    border-radius: var(--radius-lg);
    padding: 12px;
    text-align: center;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    will-change: transform, box-shadow;
  }

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

  .case-card:active {
    transform: scale(0.97);
  }

  .case-card:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .case-badge {
    display: inline-block;
    padding: 3px 10px;
    border-radius: var(--radius-full);
    font-size: clamp(0.6rem, 0.8vw, 0.7rem);
    font-weight: 700;
    margin-bottom: 6px;
  }

  .case-badge-green  { background: oklch(93% 0.06 145); color: var(--green-700); }
  .case-badge-blue   { background: var(--primary-100); color: var(--primary-700); }
  .case-badge-purple { background: oklch(93% 0.06 280); color: oklch(45% 0.18 280); }

  .case-name {
    font-size: clamp(0.8rem, 1vw, 0.88rem);
    font-weight: 600;
    color: var(--neutral-800);
    margin-bottom: 4px;
    font-family: var(--font-heading);
  }

  .case-result {
    font-size: clamp(0.7rem, 0.9vw, 0.78rem);
    color: var(--neutral-500);
    line-height: 1.5;
  }

  .case-result strong { color: var(--green-700); font-weight: 700; }

  /* ---------- AI Check Section ---------- */
  .ai-check-section {
    margin-bottom: 20px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.7s both;
  }

  .ai-check-card {
    background: var(--surface-0);
    border-radius: var(--radius-2xl);
    padding: 14px;
    box-shadow: var(--shadow-sm);
    will-change: transform, box-shadow;
  }

  .ai-check-title {
    font-family: var(--font-heading);
    font-size: clamp(1rem, 1.5vw, 1.2rem);
    font-weight: 700;
    color: var(--neutral-900);
    margin-bottom: 4px;
  }

  .ai-check-desc {
    font-size: clamp(0.8rem, 1vw, 0.88rem);
    color: var(--neutral-600);
    margin-bottom: 10px;
    line-height: 1.7;
  }

  .ai-check-links {
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-bottom: 10px;
  }

  .ai-check-link {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 14px;
    background: var(--surface-50);
    border-radius: var(--radius-md);
    font-size: clamp(0.75rem, 1vw, 0.82rem);
    color: var(--neutral-700);
    font-weight: 500;
    transition: all var(--transition-base);
    text-decoration: none;
    box-shadow: var(--shadow-sm);
  }

  .ai-check-link:hover {
    background: var(--primary-50);
    color: var(--primary-700);
    box-shadow: var(--shadow-md);
  }

  .ai-check-link:active {
    transform: scale(0.97);
  }

  .ai-check-link:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .ai-check-link-icon {
    width: 20px;
    height: 20px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    flex-shrink: 0;
  }

  .ai-check-divider {
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 10px 0;
    font-size: clamp(0.7rem, 0.9vw, 0.78rem);
    color: var(--neutral-400);
  }

  .ai-check-divider::before,
  .ai-check-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--neutral-200);
  }

  /* ---------- Wechat Section ---------- */
  .wechat-section {
    margin-bottom: 20px;
    animation: fadeInUp 0.6s var(--ease-out-expo) 0.75s both;
  }

  .wechat-card {
    background: var(--surface-0);
    border-radius: var(--radius-2xl);
    padding: 14px;
    text-align: center;
    box-shadow: var(--shadow-sm);
    will-change: transform, box-shadow;
  }

  .wechat-icon { font-size: 40px; margin-bottom: 6px; }

  .wechat-title {
    font-family: var(--font-heading);
    font-size: clamp(1rem, 1.5vw, 1.2rem);
    font-weight: 700;
    color: var(--green-700);
    margin-bottom: 4px;
  }

  .wechat-desc {
    font-size: clamp(0.8rem, 1vw, 0.88rem);
    color: var(--neutral-600);
    margin-bottom: 10px;
    line-height: 1.7;
  }

  .wechat-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 24px;
    background: var(--green-600);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    border-radius: var(--radius-full);
    font-size: 13px;
    font-weight: 600;
    box-shadow: 0 2px 4px oklch(0% 0 0 / 0.08), 0 4px 12px oklch(52% 0.16 145 / 0.25);
    transition: all var(--transition-base);
    cursor: pointer;
    border: none;
    text-decoration: none;
    min-height: 44px;
  }

  .wechat-btn:hover {
    background: var(--green-700);
    box-shadow: 0 4px 8px oklch(0% 0 0 / 0.10), 0 8px 24px oklch(44% 0.14 145 / 0.30);
    transform: translateY(-2px);
  }

  .wechat-btn:active {
    transform: scale(0.97);
    box-shadow: var(--shadow-md);
  }

  .wechat-btn:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  .wechat-hint {
    font-size: clamp(0.65rem, 0.9vw, 0.75rem);
    color: var(--neutral-400);
    margin-top: 6px;
  }

  /* ---------- FAQ Section ---------- */
  .faq-section {
    padding: clamp(20px, 5vw, 40px) 24px;
    max-width: 640px;
    margin: 0 auto;
    background: var(--surface-50);
  }

  .faq-section h2 {
    font-family: var(--font-heading);
    font-size: clamp(1rem, 2vw, 1.3rem);
    font-weight: 700;
    color: var(--neutral-900);
    margin-bottom: 12px;
    text-align: center;
  }

  .faq-list {
    display: flex;
    flex-direction: column;
    gap: 6px;
  }

  .faq-item {
    background: var(--surface-0);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: box-shadow var(--transition-base);
    box-shadow: var(--shadow-sm);
  }

  .faq-item:hover {
    box-shadow: var(--shadow-md);
  }

  .faq-item summary {
    font-weight: 600;
    font-size: clamp(0.85rem, 1.1vw, 0.95rem);
    color: var(--neutral-900);
    cursor: pointer;
    padding: 10px 12px;
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    user-select: none;
    min-height: 44px;
    transition: color var(--transition-base);
  }

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

  .faq-item summary::after {
    content: '';
    display: inline-block;
    width: 8px;
    height: 8px;
    border-right: 2px solid var(--neutral-400);
    border-bottom: 2px solid var(--neutral-400);
    transform: rotate(-45deg);
    transition: transform 0.25s var(--ease-out-expo);
    flex-shrink: 0;
  }

  .faq-item[open] summary::after { transform: rotate(45deg); }

  .faq-item summary:hover { color: var(--primary-600); }

  .faq-item summary:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: -2px;
  }

  .faq-answer { padding: 0 12px 10px; }

  .faq-answer p {
    font-size: clamp(0.8rem, 1vw, 0.88rem);
    color: var(--neutral-600);
    line-height: 1.7;
    margin: 0;
  }

  /* ---------- Footer：CSS Grid ---------- */
  footer {
    background: var(--surface-0);
    box-shadow: 0 -1px 0 oklch(0% 0 0 / 0.04);
    padding: clamp(16px, 3vw, 24px) 0 72px;
  }

  .footer-center {
    text-align: center;
    padding: 20px 24px 80px;
    max-width: 640px;
    margin: 0 auto;
  }

  .footer-company {
    font-size: clamp(0.75rem, 0.9vw, 0.85rem);
    color: var(--neutral-500);
    margin-bottom: 4px;
  }

  .footer-phone a {
    font-size: clamp(0.75rem, 0.9vw, 0.85rem);
    color: var(--primary-600);
    text-decoration: none;
    margin-bottom: 8px;
    display: inline-block;
  }

  .footer-note {
    font-size: clamp(0.62rem, 0.75vw, 0.7rem);
    color: var(--neutral-400);
    margin-bottom: 6px;
  }

  .footer-icp {
    margin-bottom: 4px;
  }
  .footer-icp a {
    font-size: clamp(0.6rem, 0.7vw, 0.68rem);
    color: var(--neutral-400);
    text-decoration: none;
    transition: color var(--transition-base);
  }
  .footer-icp a:hover {
    color: var(--primary-600);
  }

  .footer-links {
    font-size: clamp(0.6rem, 0.7vw, 0.68rem);
    color: var(--neutral-400);
  }
  .footer-links a {
    color: var(--neutral-400);
    text-decoration: none;
    transition: color var(--transition-base);
  }
  .footer-links a:hover {
    color: var(--primary-600);
  }
  .footer-sep {
    margin: 0 6px;
    color: var(--neutral-300);
  }

  /* ---------- Bottom Nav ---------- */
  .bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--surface-0);
    box-shadow: 0 -2px 12px oklch(0% 0 0 / 0.06);
    z-index: 40;
    padding-bottom: env(safe-area-inset-bottom);
  }

  .bottom-nav-inner {
    display: flex;
    justify-content: space-around;
    align-items: center;
    max-width: 640px;
    margin: 0 auto;
    height: 56px;
  }

  .nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 3px;
    padding: 4px 16px;
    color: var(--neutral-500);
    transition: color var(--transition-base);
    text-decoration: none;
    min-height: 44px;
  }

  .nav-item:hover { color: var(--primary-600); }

  .nav-item:active {
    transform: scale(0.97);
  }

  .nav-item:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
    border-radius: var(--radius-sm);
  }

  .nav-item.active { color: var(--primary-600); }

  .nav-item.highlight {
    color: #ef4444;
  }
  .nav-item.highlight .nav-icon {
    width: 20px;
    height: 20px;
  }
  .nav-item.highlight .nav-label {
    font-size: clamp(0.55rem, 0.7vw, 0.62rem);
    font-weight: 500;
    color: #ef4444;
  }
  .nav-item.highlight .nav-label .hot-emoji {
    font-size: 0.7em;
    vertical-align: middle;
  }
  .nav-item.highlight .nav-label .hot-emoji {
    font-size: inherit;
    vertical-align: middle;
  }

  .nav-item.highlight .highlight-glow {
    position: absolute;
    top: -2px;
    right: -2px;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: #f59e0b;
    animation: pulse-glow 1.5s ease-in-out infinite;
  }

  @keyframes pulse-glow {
    0%, 100% { opacity: 0.6; transform: scale(1); }
    50% { opacity: 1; transform: scale(1.3); }
  }

  .nav-icon { width: 20px; height: 20px; }

  .nav-label {
    font-size: clamp(0.55rem, 0.7vw, 0.62rem);
    font-weight: 500;
  }

  .nav-badge {
    display: inline-block;
    background: var(--primary-500);
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    font-size: clamp(0.5rem, 0.7vw, 0.56rem);
    font-weight: 700;
    padding: 2px 7px;
    border-radius: var(--radius-full);
    line-height: 14px;
    margin-left: 5px;
    vertical-align: middle;
    letter-spacing: 0.04em;
    box-shadow: 0 0 0 1.5px oklch(60% 0.18 245 / 0.35), 0 0 8px oklch(60% 0.18 245 / 0.25);
    animation: navBadgeGlow 2.5s ease-in-out infinite;
    position: relative;
  }

  /* ---------- Chat Button ---------- */
  .chat-button {
    position: fixed;
    bottom: 80px;
    right: 24px;
    width: 52px;
    height: 52px;
    background: var(--primary-600);
    border-radius: 50%;
    box-shadow: 0 4px 12px oklch(0% 0 0 / 0.10), 0 4px 16px oklch(52% 0.16 245 / 0.30);
    display: flex;
    align-items: center;
    justify-content: center;
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    z-index: 99998;
    transition: all var(--transition-base);
    border: none;
    cursor: grab;
    animation: fadeInScale 0.6s var(--ease-out-expo);
    text-decoration: none;
    touch-action: none;
    user-select: none;
    -webkit-user-select: none;
  }

  .chat-button:active {
    cursor: grabbing;
  }

  .chat-button:hover {
    transform: scale(1.08);
    box-shadow: 0 8px 24px oklch(0% 0 0 / 0.12), 0 8px 24px oklch(44% 0.14 245 / 0.35);
    background: var(--primary-700);
  }

  .chat-button:active {
    transform: scale(0.97);
  }

  .chat-button:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }

  /* ---------- Modal ---------- */
  .modal-overlay {
    position: fixed;
    inset: 0;
    background: oklch(0% 0 0 / 0.40);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 50;
    padding: 16px;
    backdrop-filter: blur(6px);
    -webkit-backdrop-filter: blur(6px);
  }

  .modal-overlay.hidden { display: none; }

  .modal {
    background: var(--surface-0);
    border-radius: var(--radius-2xl);
    box-shadow: 0 24px 48px oklch(0% 0 0 / 0.12), 0 8px 16px oklch(0% 0 0 / 0.06);
    width: 100%;
    max-width: 420px;
    padding: 24px;
    position: relative;
    animation: fadeInScale 0.35s var(--ease-out-expo);
  }

  .modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 16px;
  }

  .modal-title-group {
    display: flex;
    align-items: center;
    gap: 14px;
  }

  .modal-icon {
    width: 52px;
    height: 52px;
    border-radius: var(--radius-md);
    background: var(--primary-600);
    display: flex;
    align-items: center;
    justify-content: center;
    color: light-dark(oklch(100% 0 0), oklch(100% 0 0));
    flex-shrink: 0;
  }

  .modal-icon svg { width: 26px; height: 26px; }

  .modal-title {
    font-family: var(--font-heading);
    font-size: clamp(1.1rem, 2vw, 1.3rem);
    font-weight: 700;
    color: var(--neutral-900);
    margin: 0;
  }

  .modal-subtitle {
    font-size: clamp(0.7rem, 0.9vw, 0.78rem);
    color: var(--neutral-500);
    margin: 0;
  }

  .modal-close {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--neutral-500);
    transition: all var(--transition-base);
    flex-shrink: 0;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 20px;
    min-width: 44px;
    min-height: 44px;
  }

  .modal-close:hover {
    background: var(--surface-50);
    color: var(--neutral-900);
  }

  .modal-close:active {
    transform: scale(0.97);
  }

  .modal-close:focus-visible {
    outline: 2px solid var(--brand-500);
    outline-offset: 2px;
  }
}

/* ============================================
   @layer utilities — 响应式，will-change
   ============================================ */
@layer utilities {

  /* ---------- will-change 性能优化 ---------- */
  .card-a,
  .card-b,
  .case-card,
  .free-card,
  .hosting-card,
  .wechat-card,
  .ai-check-card {
    will-change: transform, box-shadow;
  }

  /* ---------- 响应式 ==== */

  /* ≥640px (sm) */
  @media (min-width: 640px) {
    .hero-title { }
    .hero-subtitle { }
    .highlight-text { }
    .btn-group { flex-direction: row; justify-content: center; }
    .case-grid { grid-template-columns: repeat(3, 1fr); }
  }

  /* ≥768px (md) */
  @media (min-width: 768px) {
    .hero-section { padding: 28px 32px 24px; }
    .free-card,
    .hosting-card { padding: 24px; }
  }

  /* ≥1024px (lg) */
  @media (min-width: 1024px) {
    .container { max-width: 640px; }
  }

  /* ≤767px 移动端适配 */
  @media (max-width: 767px) {
    body { font-size: clamp(0.85rem, 1.2vw, 0.95rem); line-height: 1.7; }
    .container { padding: 0 16px; }
    .card-grid {
      grid-template-columns: 30% 1fr;
    }
    .card-col-a { }
    .hero-section { padding: 24px 16px 20px; }
    .hero-title { font-size: clamp(1.4rem, 4vw, 1.8rem); }
    .hero-subtitle { font-size: clamp(0.85rem, 1.5vw, 1rem); }
    .highlight-text { font-size: clamp(0.85rem, 1.2vw, 0.95rem); }
    .section-title,
    .faq-section h2 { font-size: clamp(1rem, 2vw, 1.2rem); }
    h3 { font-size: clamp(1rem, 1.8vw, 1.2rem); }
    p, li { font-size: clamp(0.8rem, 1vw, 0.88rem); }
    .btn {
      display: block;
      width: 100%;
      text-align: center;
      padding: 10px 16px;
      font-size: 13px;
    }
    .modal {
      width: 100%;
      max-width: 100%;
      margin: 12px;
      padding: 20px;
      border-radius: var(--radius-lg);
    }

    .platform-list { gap: 8px; flex-wrap: wrap; }
    .case-grid { grid-template-columns: 1fr; }
    .chat-button { bottom: 60px; right: 16px; width: 48px; height: 48px; }
  }

  @media (max-width: 480px) {
    body { font-size: clamp(0.8rem, 1vw, 0.88rem); }
    .hero-section { padding: 20px 12px 16px; }
    .container { padding: 0 12px; }
    .hero-title { font-size: clamp(1.3rem, 4vw, 1.5rem); }
    .section-title,
    .faq-section h2 { font-size: clamp(0.95rem, 1.8vw, 1.1rem); }
    .btn {
      padding: 10px 14px;
      font-size: 12px;
    }
    .free-card,
    .hosting-card { padding: 14px; }

    .bottom-nav-inner { gap: 0; }
    .nav-item { padding: 4px 10px; }
  }
}