/* roulang page: index */
:root {
      --primary-black: #1A1A1A;
      --accent-gold: #D4AF37;
      --bg-warm: #FAFAFA;
      --card-white: #FFFFFF;
      --title-dark: #2C2C2C;
      --body-gray: #5C5C5C;
      --border-light: #E8E8E8;
      --footer-bg: #F5F5F5;
      --deep-bg: #1A1A1A;
      --text-muted: #B0B0B0;
      --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
      --font-number: "Inter", "SF Pro Display", sans-serif;
      --radius-card: 8px;
      --radius-btn: 4px;
      --shadow-card: 0 8px 30px rgba(0,0,0,0.06);
      --shadow-nav: 0 2px 20px rgba(0,0,0,0.04);
      --shadow-gold: 0 6px 18px rgba(212,175,55,0.25);
      --transition-smooth: 0.25s ease;
    }
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-warm);
      color: var(--body-gray);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      scroll-behavior: smooth;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      color: inherit;
      text-decoration: none;
    }
    button, .button {
      cursor: pointer;
      font-family: var(--font-sans);
      border: none;
      outline: none;
      transition: var(--transition-smooth);
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 32px;
    }
    @media (max-width: 640px) {
      .container {
        padding: 0 20px;
      }
    }
    /* 导航栏 */
    .nav-bar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 72px;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 32px;
      z-index: 100;
      transition: box-shadow 0.3s ease, background 0.3s ease;
      border-bottom: 1px solid transparent;
    }
    .nav-scrolled {
      box-shadow: var(--shadow-nav);
      background: rgba(255,255,255,0.98);
      border-bottom: 1px solid var(--border-light);
    }
    .logo {
      font-family: var(--font-number);
      font-weight: 700;
      font-size: 24px;
      letter-spacing: -0.5px;
      color: var(--primary-black);
    }
    .logo span {
      color: var(--accent-gold);
    }
    .nav-links {
      display: flex;
      gap: 40px;
      align-items: center;
    }
    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--body-gray);
      position: relative;
      padding: 8px 0;
      transition: color 0.2s;
    }
    .nav-links a:hover {
      color: var(--accent-gold);
    }
    .nav-links a.active {
      color: var(--primary-black);
    }
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      transform: translateX(-50%);
      width: 20px;
      height: 2px;
      background: var(--accent-gold);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 6px;
      cursor: pointer;
      background: transparent;
      border: none;
    }
    .hamburger span {
      display: block;
      height: 2px;
      background: var(--primary-black);
      transition: 0.25s;
    }
    .hamburger span:nth-child(1) { width: 20px; }
    .hamburger span:nth-child(2) { width: 14px; }
    .hamburger span:nth-child(3) { width: 20px; }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        width: 100%;
        background: rgba(255,255,255,0.98);
        flex-direction: column;
        gap: 0;
        box-shadow: var(--shadow-nav);
        backdrop-filter: blur(12px);
      }
      .nav-links.active {
        display: flex;
      }
      .nav-links a {
        padding: 16px 32px;
        border-bottom: 1px solid var(--border-light);
      }
      .hamburger {
        display: flex;
      }
    }
    /* 通用板块间距 */
    section {
      padding: 100px 0;
      scroll-margin-top: 72px;
    }
    @media (max-width: 640px) {
      section {
        padding: 70px 0;
      }
    }
    /* Hero 双栏 */
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
      min-height: 85vh;
      padding-top: 72px;
    }
    .hero-left {
      flex: 0 0 55%;
    }
    .hero-right {
      flex: 0 0 45%;
      position: relative;
    }
    .hero-right .image-wrapper {
      position: relative;
      transform: rotate(2deg);
      overflow: hidden;
      border-radius: 0;
    }
    .hero-right .image-wrapper img {
      width: 100%;
      height: auto;
      object-fit: cover;
      aspect-ratio: 4/3;
      border-radius: 0;
    }
    .hero-right .gold-line {
      position: absolute;
      bottom: -8px;
      left: 0;
      width: 60px;
      height: 2px;
      background: var(--accent-gold);
    }
    .hero-left h1 {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.15;
      letter-spacing: -0.5px;
      color: var(--primary-black);
      margin-bottom: 24px;
      font-family: var(--font-sans);
    }
    .hero-left .sub {
      font-size: 18px;
      line-height: 1.6;
      color: var(--body-gray);
      margin-bottom: 40px;
      max-width: 480px;
    }
    .cta-group {
      display: flex;
      align-items: center;
      gap: 24px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--accent-gold);
      color: #FFFFFF;
      padding: 14px 36px;
      font-weight: 600;
      font-size: 16px;
      border-radius: var(--radius-btn);
      box-shadow: 0 4px 12px rgba(212,175,55,0.2);
      display: inline-block;
      text-align: center;
      transition: all 0.25s;
    }
    .btn-primary:hover {
      background: #c4a02e;
      box-shadow: var(--shadow-gold);
      transform: translateY(-2px);
      color: #fff;
    }
    .btn-ghost {
      font-weight: 600;
      color: var(--primary-black);
      border-bottom: 1.5px solid var(--primary-black);
      padding-bottom: 2px;
      transition: 0.2s;
    }
    .btn-ghost:hover {
      color: var(--accent-gold);
      border-color: var(--accent-gold);
    }
    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column;
        gap: 40px;
        min-height: auto;
      }
      .hero-left, .hero-right {
        flex: 0 0 100%;
      }
      .hero-left h1 {
        font-size: 36px;
      }
      .hero-right .image-wrapper {
        transform: rotate(0);
      }
    }
    /* 亮点网格 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 40px;
    }
    .feature-card {
      border: 1px solid var(--border-light);
      padding: 32px;
      background: transparent;
      transition: all var(--transition-smooth);
      border-radius: var(--radius-card);
    }
    .feature-card:hover {
      border-color: var(--accent-gold);
      transform: translateY(-4px);
      box-shadow: var(--shadow-card);
    }
    .feature-icon {
      font-size: 24px;
      color: var(--accent-gold);
      margin-bottom: 16px;
      line-height: 1;
    }
    .feature-card h3 {
      font-size: 22px;
      font-weight: 600;
      color: var(--title-dark);
      margin-bottom: 8px;
    }
    .feature-card p {
      color: var(--body-gray);
      font-size: 15px;
    }
    @media (max-width: 768px) {
      .features-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 24px;
      }
    }
    @media (max-width: 520px) {
      .features-grid {
        grid-template-columns: 1fr;
      }
    }
    /* 案例瀑布 */
    .cases-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
    }
    .case-card {
      background: var(--card-white);
      border-radius: var(--radius-card);
      overflow: hidden;
      transition: all var(--transition-smooth);
    }
    .case-card:nth-child(odd) {
      margin-top: 0;
    }
    .case-card:nth-child(even) {
      margin-top: 60px;
    }
    .case-img {
      height: 240px;
      overflow: hidden;
      border-radius: 0;
    }
    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.3s ease;
    }
    .case-card:hover .case-img img {
      transform: scale(1.03);
    }
    .case-info {
      padding: 20px;
    }
    .case-info h4 {
      font-size: 18px;
      font-weight: 600;
      color: var(--title-dark);
      margin-bottom: 8px;
    }
    .tag {
      display: inline-block;
      font-size: 12px;
      color: var(--accent-gold);
      background: rgba(212,175,55,0.08);
      padding: 2px 10px;
      border-radius: 2px;
      font-weight: 500;
    }
    @media (max-width: 640px) {
      .cases-grid {
        grid-template-columns: 1fr;
        gap: 30px;
      }
      .case-card:nth-child(even) {
        margin-top: 0;
      }
    }
    /* 方案对比 */
    .compare-panel {
      display: flex;
      border-top: 1px solid var(--border-light);
      border-bottom: 1px solid var(--border-light);
    }
    .compare-left, .compare-right {
      flex: 1;
      padding: 40px 0;
    }
    .compare-left {
      border-right: 1px solid var(--border-light);
      padding-right: 40px;
    }
    .compare-right {
      padding-left: 40px;
    }
    .compare-title {
      font-size: 20px;
      font-weight: 700;
      margin-bottom: 24px;
    }
    .compare-left .compare-title {
      color: var(--body-gray);
    }
    .compare-right .compare-title {
      color: var(--primary-black);
    }
    .compare-list {
      list-style: none;
    }
    .compare-list li {
      margin-bottom: 18px;
      font-size: 15px;
      display: flex;
      align-items: baseline;
      gap: 12px;
    }
    .left-marker {
      color: #9A9A9A;
      font-weight: 500;
    }
    .right-marker {
      width: 6px;
      height: 6px;
      background: var(--accent-gold);
      border-radius: 50%;
      margin-top: 8px;
      flex-shrink: 0;
    }
    @media (max-width: 640px) {
      .compare-panel {
        flex-direction: column;
      }
      .compare-left {
        border-right: none;
        border-bottom: 1px solid var(--border-light);
        padding-right: 0;
        padding-bottom: 30px;
      }
      .compare-right {
        padding-left: 0;
        padding-top: 30px;
      }
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      padding: 20px 0;
      font-size: 18px;
      font-weight: 600;
      color: var(--title-dark);
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      user-select: none;
    }
    .faq-icon {
      font-size: 18px;
      transition: transform 0.25s;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s;
      background: #F5F5F5;
      padding: 0 20px;
      margin-left: 0;
      border-left: 2px solid transparent;
    }
    .faq-item.open .faq-answer {
      max-height: 300px;
      padding: 20px;
      border-left: 2px solid var(--accent-gold);
    }
    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }
    /* CTA 横幅 */
    .cta-banner {
      background: var(--deep-bg);
      padding: 80px 0;
      text-align: center;
    }
    .cta-banner h2 {
      color: #fff;
      font-size: 36px;
      font-weight: 700;
      margin-bottom: 16px;
    }
    .gold-divider {
      width: 40px;
      height: 2px;
      background: var(--accent-gold);
      margin: 0 auto 20px;
    }
    .cta-banner p {
      color: var(--text-muted);
      margin-bottom: 32px;
    }
    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      background: var(--footer-bg);
      padding: 60px 0;
      border-top: 1px solid var(--border-light);
    }
    .footer-col h5 {
      font-size: 14px;
      font-weight: 700;
      color: var(--primary-black);
      margin-bottom: 16px;
    }
    .footer-col p, .footer-col a {
      font-size: 14px;
      color: var(--body-gray);
      display: block;
      margin-bottom: 8px;
      transition: color 0.2s;
    }
    .footer-col a:hover {
      color: var(--accent-gold);
    }
    .copyright {
      background: #EEEEEE;
      text-align: center;
      padding: 16px 0;
      font-size: 12px;
      color: #888;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 30px;
      }
    }
    @media (max-width: 520px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }
    .section-title {
      font-size: 36px;
      font-weight: 600;
      color: var(--title-dark);
      margin-bottom: 16px;
    }
    .section-sub {
      color: var(--body-gray);
      margin-bottom: 48px;
      max-width: 600px;
    }