/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary: #800020;
      --primary-deep: #5a0016;
      --primary-light: #fdf5f5;
      --accent: #D4AF37;
      --accent-light: #fbf3d5;
      --bg-white: #FFFFFF;
      --bg-light: #F7F5F4;
      --bg-dark: #1A0000;
      --text-dark: #1a1a1a;
      --text-body: #333333;
      --text-muted: #777777;
      --border-soft: rgba(0,0,0,0.06);
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-hover: 0 8px 30px rgba(0,0,0,0.08);
      --radius-md: 12px;
      --radius-sm: 8px;
      --font-serif: 'Noto Serif SC', 'Times New Roman', serif;
      --font-sans: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
      --transition-base: 0.3s ease;
      --max-width: 1280px;
    }

    /* ----- 基础重置 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: var(--font-sans);
      background: var(--bg-white);
      color: var(--text-body);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }
    img {
      max-width: 100%;
      display: block;
      height: auto;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s;
    }
    button, input, textarea {
      font-family: inherit;
    }

    /* ----- 容器与布局工具 ----- */
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    .section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      .section {
        padding: 70px 0;
      }
      .container {
        padding: 0 20px;
      }
    }

    /* ----- 导航（沉浸式） ----- */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      background: transparent;
      transition: background var(--transition-base), box-shadow var(--transition-base);
      height: 72px;
      display: flex;
      align-items: center;
    }
    .header.scrolled {
      background: var(--bg-white);
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }
    .nav-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      font-family: var(--font-serif);
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--bg-white);
      letter-spacing: 1px;
      transition: color var(--transition-base);
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo span {
      color: var(--accent);
    }
    .header.scrolled .logo {
      color: var(--primary);
    }
    .header.scrolled .logo span {
      color: var(--accent);
    }
    .nav-links {
      display: flex;
      gap: 2.2rem;
      align-items: center;
      list-style: none;
      font-weight: 500;
      font-size: 0.95rem;
    }
    .nav-links a {
      color: rgba(255,255,255,0.9);
      padding: 6px 0;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }
    .header.scrolled .nav-links a {
      color: var(--text-dark);
    }
    .nav-links a:hover {
      color: var(--accent);
      border-bottom-color: var(--accent);
    }
    .header.scrolled .nav-links a:hover {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }

    /* 汉堡菜单 */
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 10px;
      z-index: 1100;
    }
    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: white;
      transition: 0.3s;
    }
    .header.scrolled .hamburger span {
      background: var(--primary);
    }
    .hamburger span:nth-child(2) {
      width: 16px;
      align-self: flex-end;
    }
    .mobile-menu {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(10, 0, 0, 0.92);
      backdrop-filter: blur(12px);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 2.8rem;
      transform: translateX(100%);
      transition: transform 0.4s ease;
      z-index: 1050;
      list-style: none;
    }
    .mobile-menu.active {
      transform: translateX(0);
    }
    .mobile-menu a {
      color: white;
      font-size: 2rem;
      font-weight: 500;
      opacity: 0;
      transform: translateX(30px);
      transition: opacity 0.3s ease, transform 0.3s ease;
    }
    .mobile-menu.active a {
      opacity: 1;
      transform: translateX(0);
    }
    .mobile-menu a:nth-child(1) { transition-delay: 0.1s; }
    .mobile-menu a:nth-child(2) { transition-delay: 0.2s; }
    .mobile-menu a:nth-child(3) { transition-delay: 0.3s; }
    .mobile-menu a:nth-child(4) { transition-delay: 0.4s; }
    .mobile-menu a:nth-child(5) { transition-delay: 0.5s; }
    .mobile-menu a:nth-child(6) { transition-delay: 0.6s; }

    @media (max-width: 1023px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
    }

    /* ----- Hero 首屏 ----- */
    .hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, #1a0a0a 0%, #2d0f0f 100%);
      position: relative;
      overflow: hidden;
      color: white;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 3rem;
      align-items: center;
    }
    .hero-content h1 {
      font-family: var(--font-serif);
      font-size: clamp(3rem, 6vw, 4.5rem);
      font-weight: 700;
      line-height: 1.2;
      color: white;
      margin-bottom: 1.5rem;
      letter-spacing: -0.5px;
    }
    .hero-content h1 span {
      color: var(--accent);
    }
    .hero-sub {
      font-size: 1.2rem;
      color: rgba(255,255,255,0.75);
      margin-bottom: 2.5rem;
      max-width: 450px;
    }
    .btn-group {
      display: flex;
      gap: 1.2rem;
      flex-wrap: wrap;
    }
    .btn {
      display: inline-block;
      font-weight: 600;
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      transition: all 0.25s ease;
      text-align: center;
      font-size: 1rem;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border: 2px solid var(--primary);
    }
    .btn-primary:hover {
      background: var(--primary-deep);
      border-color: var(--primary-deep);
      box-shadow: 0 8px 18px rgba(128,0,32,0.3);
    }
    .btn-outline {
      background: transparent;
      color: white;
      border: 2px solid rgba(255,255,255,0.5);
    }
    .btn-outline:hover {
      background: white;
      color: var(--primary);
      border-color: white;
    }
    .hero-image {
      position: relative;
      border-radius: 24px;
      overflow: hidden;
      box-shadow: 0 20px 40px rgba(0,0,0,0.3);
    }
    .hero-image img {
      width: 100%;
      height: auto;
      object-fit: cover;
      aspect-ratio: 4/3;
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
      }
      .hero-sub {
        margin-left: auto;
        margin-right: auto;
      }
      .btn-group {
        justify-content: center;
      }
      .hero-image {
        max-width: 320px;
        margin: 0 auto;
      }
    }

    /* ----- 亮点网格（杂志式） ----- */
    .highlights {
      background: var(--bg-white);
    }
    .section-title {
      font-family: var(--font-serif);
      font-size: 2.5rem;
      font-weight: 600;
      color: var(--text-dark);
      margin-bottom: 3rem;
      text-align: center;
    }
    .highlight-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr 1fr;
      gap: 24px;
    }
    .highlight-card {
      background: var(--bg-light);
      border-radius: var(--radius-md);
      padding: 2rem;
      transition: all 0.3s;
      border: 1px solid transparent;
      display: flex;
      flex-direction: column;
      justify-content: center;
    }
    .highlight-card.large {
      grid-row: span 2;
      background: white;
      border: 1px solid var(--border-soft);
    }
    .highlight-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
      border-color: rgba(212,175,55,0.2);
    }
    .icon-circle {
      width: 48px;
      height: 48px;
      background: rgba(212,175,55,0.1);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 1.2rem;
      color: var(--accent);
      font-size: 1.8rem;
    }
    .highlight-card h3 {
      font-family: var(--font-sans);
      font-weight: 600;
      font-size: 1.4rem;
      margin-bottom: 0.5rem;
    }
    .highlight-card p {
      color: var(--text-muted);
      font-size: 0.95rem;
    }
    @media (max-width: 1023px) {
      .highlight-grid {
        grid-template-columns: 1fr 1fr;
      }
      .highlight-card.large {
        grid-column: span 2;
      }
    }
    @media (max-width: 640px) {
      .highlight-grid {
        grid-template-columns: 1fr;
      }
      .highlight-card.large {
        grid-column: span 1;
      }
    }

    /* ----- 案例瀑布流 ----- */
    .cases {
      background: var(--bg-light);
    }
    .case-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .case-card {
      border-radius: var(--radius-md);
      overflow: hidden;
      background: white;
      box-shadow: var(--shadow-card);
      transition: all 0.4s;
      position: relative;
    }
    .case-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-hover);
    }
    .case-img {
      position: relative;
      overflow: hidden;
      aspect-ratio: 3/4;
    }
    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.4s;
    }
    .case-card:hover .case-img img {
      transform: scale(1.03);
    }
    .case-caption {
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      padding: 1.5rem;
      background: linear-gradient(transparent, rgba(0,0,0,0.7));
      color: white;
      font-weight: 500;
    }
    @media (max-width: 768px) {
      .case-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    @media (max-width: 520px) {
      .case-grid {
        grid-template-columns: 1fr;
      }
    }

    /* ----- 方案对比 ----- */
    .compare-container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 2rem;
      align-items: start;
    }
    .compare-card {
      background: white;
      border-radius: var(--radius-md);
      padding: 2rem;
      box-shadow: var(--shadow-card);
    }
    .compare-card.premium {
      background: var(--primary-light);
      border: 1px solid rgba(128,0,32,0.15);
      box-shadow: 0 8px 24px rgba(128,0,32,0.08);
    }
    .compare-card h3 {
      font-size: 1.8rem;
      font-weight: 600;
      margin-bottom: 1.5rem;
      display: flex;
      align-items: center;
      gap: 0.5rem;
    }
    .compare-list {
      list-style: none;
    }
    .compare-list li {
      margin-bottom: 1rem;
      display: flex;
      align-items: center;
      gap: 12px;
    }
    @media (max-width: 768px) {
      .compare-container {
        grid-template-columns: 1fr;
      }
    }

    /* ----- FAQ 手风琴 ----- */
    .faq {
      background: var(--bg-light);
    }
    .faq-list {
      max-width: 720px;
      margin: 0 auto;
    }
    .faq-item {
      background: white;
      border-radius: var(--radius-sm);
      margin-bottom: 12px;
      box-shadow: 0 2px 8px rgba(0,0,0,0.02);
      overflow: hidden;
    }
    .faq-question {
      width: 100%;
      background: none;
      border: none;
      padding: 20px;
      font-size: 1.1rem;
      font-weight: 600;
      display: flex;
      align-items: center;
      gap: 15px;
      cursor: pointer;
      text-align: left;
      color: var(--text-dark);
    }
    .faq-icon {
      width: 20px;
      height: 20px;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: transform 0.3s;
      color: var(--accent);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      background: #fafaf8;
      padding: 0 20px;
    }
    .faq-answer p {
      padding: 0 0 20px 35px;
      color: var(--text-body);
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
    }

    /* ----- CTA 尾屏 ----- */
    .cta-dark {
      background: var(--bg-dark);
      color: white;
    }
    .cta-form {
      max-width: 560px;
      margin: 2rem auto 0;
    }
    .input-line {
      width: 100%;
      background: transparent;
      border: none;
      border-bottom: 1px solid #555;
      padding: 14px 8px;
      margin-bottom: 1.5rem;
      color: white;
      font-size: 1rem;
      outline: none;
      transition: border 0.2s;
    }
    .input-line:focus {
      border-bottom: 2px solid var(--primary);
    }
    .btn-submit {
      background: var(--primary);
      color: white;
      border: none;
      padding: 16px;
      width: 100%;
      border-radius: var(--radius-sm);
      font-weight: 600;
      cursor: pointer;
      transition: background 0.2s;
    }
    .btn-submit:hover {
      background: var(--primary-deep);
    }

    /* ----- 页脚 ----- */
    .footer {
      background: #0d0d0d;
      color: #aaa;
      padding: 60px 0 20px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr 1fr 1fr;
      gap: 2rem;
    }
    .footer-logo {
      font-family: var(--font-serif);
      font-size: 1.6rem;
      color: white;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }