/* roulang page: index */
/* ----- 设计变量 / 基础重置 ----- */
    :root {
      --primary-black: #1A1A1A;
      --accent-red: #C41E3A;
      --bg-warm: #F7F5F0;
      --card-white: #FFFFFF;
      --text-charcoal: #2C2C2C;
      --text-gray: #5A5A5A;
      --border-light: rgba(0,0,0,0.04);
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 6px 16px rgba(0,0,0,0.04);
      --shadow-hover: 0 8px 30px rgba(0,0,0,0.08);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 20px;
      --font-title: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --font-body: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --font-mono: 'Inter', 'SF Pro Display', system-ui, sans-serif;
      --max-width: 1280px;
      --padding-h: 40px;
      --section-gap: 120px;
      --section-gap-mobile: 80px;
    }

    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-body);
      background-color: var(--bg-warm);
      color: var(--text-charcoal);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
    }

    /* 容器 */
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 var(--padding-h);
    }

    /* 标题层级 */
    h1 {
      font-family: var(--font-title);
      font-weight: 700;
      font-size: clamp(40px, 6vw, 56px);
      letter-spacing: -0.02em;
      color: var(--primary-black);
      line-height: 1.2;
    }

    h2 {
      font-family: var(--font-title);
      font-weight: 600;
      font-size: clamp(32px, 5vw, 40px);
      letter-spacing: -0.02em;
      color: var(--primary-black);
      margin-bottom: 1.2rem;
    }

    h3 {
      font-family: var(--font-title);
      font-weight: 600;
      font-size: 1.25rem;
      color: var(--primary-black);
    }

    .section-title {
      text-align: left;
      margin-bottom: 3rem;
    }

    /* 按钮系统 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      transition: all 0.3s ease;
      border: 1.5px solid transparent;
      letter-spacing: 0.3px;
    }

    .btn-primary {
      background-color: var(--accent-red);
      color: white;
      border-color: var(--accent-red);
    }

    .btn-primary:hover {
      transform: scale(1.03);
      box-shadow: 0 10px 25px rgba(196, 30, 58, 0.3);
    }

    .btn-outline {
      background: transparent;
      border-color: var(--primary-black);
      color: var(--primary-black);
    }

    .btn-outline:hover {
      background-color: rgba(196, 30, 58, 0.05);
      border-color: var(--accent-red);
      color: var(--accent-red);
      transform: translateY(-2px);
    }

    .btn-light {
      background: transparent;
      border-color: white;
      color: white;
    }
    .btn-light:hover {
      background: rgba(255,255,255,0.1);
      border-color: white;
      color: white;
    }

    /* 导航 Dock */
    .nav-dock {
      position: fixed;
      top: 24px;
      left: 50%;
      transform: translateX(-50%);
      width: calc(100% - 40px);
      max-width: 1000px;
      background: rgba(255,255,255,0.7);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border: 1px solid var(--border-light);
      border-radius: 40px;
      padding: 8px 24px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      z-index: 100;
      transition: background 0.3s, box-shadow 0.3s;
    }

    .nav-dock.scrolled {
      background: rgba(255,255,255,0.92);
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }

    .logo {
      font-family: var(--font-title);
      font-weight: 700;
      font-size: 1.4rem;
      color: var(--primary-black);
      white-space: nowrap;
      letter-spacing: -0.3px;
    }

    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
      font-weight: 500;
      font-size: 0.9rem;
      color: var(--text-charcoal);
    }

    .nav-links a {
      position: relative;
      padding: 4px 0;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--accent-red);
      transform: scaleX(0);
      transform-origin: left;
      transition: transform 0.3s;
    }

    .nav-links a:hover::after {
      transform: scaleX(1);
    }

    .nav-cta {
      background: var(--accent-red);
      color: white;
      padding: 10px 24px;
      border-radius: 30px;
      font-weight: 600;
      font-size: 0.9rem;
      transition: transform 0.2s, box-shadow 0.2s;
    }
    .nav-cta:hover {
      transform: scale(1.05);
      box-shadow: 0 6px 15px rgba(196,30,58,0.4);
    }

    .hamburger {
      display: none;
      background: none;
      border: none;
      font-size: 1.6rem;
      color: var(--primary-black);
    }

    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: block;
      }
      .nav-dock {
        padding: 8px 20px;
      }
    }

    /* Hero 双栏 */
    .hero {
      padding: 160px 0 100px;
      display: flex;
      align-items: center;
      gap: 3rem;
    }

    .hero-left {
      flex: 0 0 60%;
    }
    .hero-right {
      flex: 0 0 40%;
      position: relative;
    }

    .hero-right img {
      border-radius: 16px;
      box-shadow: var(--shadow-sm);
      width: 100%;
      object-fit: cover;
      aspect-ratio: 3/4;
      filter: contrast(1.1);
    }

    .hero-sub {
      font-size: 1.1rem;
      color: var(--text-gray);
      margin: 1.5rem 0 2rem;
      max-width: 450px;
    }

    .hero-buttons {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
    }

    @media (max-width: 1024px) {
      .hero {
        flex-direction: column-reverse;
        padding: 140px 0 60px;
      }
      .hero-left, .hero-right {
        flex: 1 1 auto;
        width: 100%;
      }
      .hero-right img {
        aspect-ratio: 4/3;
      }
    }

    /* 板块通用 */
    .section {
      padding: var(--section-gap) 0;
    }

    @media (max-width: 768px) {
      .section {
        padding: var(--section-gap-mobile) 0;
      }
      :root {
        --padding-h: 20px;
      }
    }

    /* 亮点网格 */
    .highlights-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

    .highlight-card {
      background: var(--card-white);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: all 0.3s ease;
    }

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

    .highlight-icon {
      font-size: 2rem;
      color: var(--accent-red);
      margin-bottom: 1.2rem;
      width: 40px;
      height: 40px;
      display: flex;
      align-items: center;
    }

    .highlight-card h3 {
      margin-bottom: 0.5rem;
      font-size: 1.3rem;
    }

    .highlight-card p {
      color: var(--text-gray);
      font-size: 0.95rem;
    }

    @media (max-width: 1024px) {
      .highlights-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 520px) {
      .highlights-grid {
        grid-template-columns: 1fr;
      }
    }

    /* 案例瀑布流 */
    .cases-masonry {
      columns: 3;
      column-gap: 24px;
    }

    .case-card {
      break-inside: avoid;
      margin-bottom: 24px;
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: 0.3s;
    }

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

    .case-img {
      width: 100%;
      display: block;
      filter: grayscale(30%);
      transition: filter 0.4s, transform 0.4s;
    }

    .case-card:hover .case-img {
      filter: grayscale(0%);
      transform: scale(1.03);
    }

    .case-info {
      padding: 20px;
    }

    .case-tags {
      display: flex;
      gap: 8px;
      margin-bottom: 10px;
    }

    .tag {
      background: #f0f0f0;
      color: var(--primary-black);
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 0.75rem;
      font-weight: 500;
    }

    .case-info h3 {
      font-size: 1.2rem;
    }

    @media (max-width: 1024px) {
      .cases-masonry {
        columns: 2;
      }
    }
    @media (max-width: 520px) {
      .cases-masonry {
        columns: 1;
      }
    }

    /* 方案对比 */
    .compare-wrapper {
      display: flex;
      align-items: stretch;
      gap: 0;
      background: white;
      border-radius: 20px;
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }

    .compare-col {
      flex: 1;
      padding: 40px;
    }

    .compare-left {
      background: #f9f9f9;
    }

    .compare-right {
      background: white;
      border-left: 2px dashed #ddd;
      position: relative;
    }

    .vs-badge {
      position: absolute;
      top: 20px;
      left: -20px;
      background: var(--accent-red);
      color: white;
      width: 40px;
      height: 40px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      z-index: 2;
    }

    .compare-item {
      display: flex;
      align-items: center;
      gap: 12px;
      margin: 24px 0;
      padding-bottom: 16px;
      border-bottom: 1px solid #eee;
    }

    .compare-right .compare-item {
      color: var(--accent-red);
      font-weight: 500;
    }

    @media (max-width: 768px) {
      .compare-wrapper {
        flex-direction: column;
      }
      .compare-right {
        border-left: none;
        border-top: 2px dashed #ddd;
      }
      .vs-badge {
        top: -20px;
        left: 20px;
      }
    }

    /* FAQ 手风琴 */
    .faq-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 30px;
    }

    .faq-item {
      border-bottom: 1px solid rgba(0,0,0,0.08);
      padding: 20px 0;
    }

    .faq-question {
      display: flex;
      align-items: baseline;
      gap: 16px;
      cursor: pointer;
      font-weight: 600;
      font-size: 1.1rem;
    }

    .faq-number {
      font-family: var(--font-mono);
      font-size: 1.6rem;
      font-weight: 700;
      color: var(--accent-red);
      min-width: 40px;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      padding-left: 56px;
      color: var(--text-gray);
      border-left: 3px solid transparent;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      border-left-color: var(--accent-red);
      margin-top: 10px;
    }

    @media (max-width: 768px) {
      .faq-grid {
        grid-template-columns: 1fr;
      }
    }

    /* CTA 深色区 */
    .cta-dark {
      background: var(--primary-black);
      color: white;
      text-align: center;
      padding: 80px 20px;
      position: relative;
    }

    .cta-dark h2 {
      color: white;
    }

    .cta-buttons {
      display: flex;
      gap: 1rem;
      justify-content: center;
      margin-top: 2rem;
      flex-wrap: wrap;
    }

    /* 页脚 */
    .footer {
      background: #EFECE6;
      padding: 60px 0 30px;
      color: var(--text-charcoal);
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
      margin-bottom: 40px;
    }

    .footer-links a {
      display: block;
      margin-bottom: 8px;
      color: var(--text-gray);
    }
    .footer-links a:hover {
      color: var(--accent-red);
    }

    .copyright {
      border-top: 1px solid rgba(0,0,0,0.1);
      padding-top: 20px;
      text-align: center;
      font-size: 0.9rem;
      color: var(--text-gray);
    }

    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }

    /* 动效辅助 */
    .fade-up {
      opacity: 0;
      transform: translateY(20px);
      transition: opacity 0.6s ease, transform 0.6s ease;
    }
    .fade-up.visible {
      opacity: 1;
      transform: translateY(0);
    }