/* roulang page: index */
:root {
      --primary-deep: #1C1C1E;
      --accent-orange: #FF4F00;
      --accent-orange-hover: #E64500;
      --silver-light: #E5E5E7;
      --bg-light: #F5F5F7;
      --white: #FFFFFF;
      --text-main: #1C1C1E;
      --text-secondary: #636366;
      --text-on-dark: #F5F5F7;
      --border-light: rgba(0,0,0,0.04);
      --shadow-card: 0 12px 30px rgba(0,0,0,0.08);
      --shadow-hover: 0 20px 35px rgba(0,0,0,0.12);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition-smooth: 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
      --font-title: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --font-body: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --container-max: 1280px;
      --header-height: 72px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: var(--font-body);
      background-color: var(--bg-light);
      color: var(--text-main);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    button, .btn {
      cursor: pointer;
      font-family: var(--font-body);
      border: none;
      outline: none;
      transition: var(--transition-smooth);
    }
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 40px;
    }
    @media (max-width: 1024px) {
      .container {
        padding: 0 32px;
      }
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 20px;
      }
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: var(--header-height);
      display: flex;
      align-items: center;
      transition: background 0.3s, backdrop-filter 0.3s;
      background: rgba(255,255,255,0.9);
      backdrop-filter: blur(10px);
      border-bottom: 1px solid rgba(0,0,0,0.02);
    }
    .header.scrolled {
      background: rgba(28,28,30,0.9);
      backdrop-filter: blur(20px);
      border-bottom: 1px solid rgba(255,255,255,0.1);
    }
    .header.scrolled .logo-text,
    .header.scrolled .nav-link {
      color: var(--text-on-dark);
    }
    .header.scrolled .hamburger span {
      background: var(--text-on-dark);
    }
    .header-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 40px;
    }
    .logo {
      font-family: var(--font-title);
      font-weight: 700;
      font-size: 1.8rem;
      letter-spacing: -0.5px;
      color: var(--primary-deep);
      transition: color 0.3s;
    }
    .logo-text {
      color: var(--primary-deep);
    }
    .nav-menu {
      display: flex;
      gap: 2.5rem;
      align-items: center;
    }
    .nav-link {
      font-weight: 500;
      font-size: 1rem;
      color: var(--primary-deep);
      transition: color 0.2s;
      position: relative;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--accent-orange);
      transition: width 0.25s ease;
    }
    .nav-link:hover::after,
    .nav-link.active::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--primary-deep);
      border-radius: 2px;
      transition: 0.3s;
    }
    @media (max-width: 768px) {
      .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 100%;
        height: 100vh;
        background: var(--primary-deep);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 2.5rem;
        transition: right 0.4s ease;
        z-index: 999;
      }
      .nav-menu.active {
        right: 0;
      }
      .nav-link {
        font-size: 1.8rem;
        color: var(--white);
      }
      .hamburger {
        display: flex;
        z-index: 1001;
      }
      .header-inner {
        padding: 0 20px;
      }
    }

    /* Hero */
    .hero {
      height: 100vh;
      min-height: 700px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      background-blend-mode: overlay;
      background-color: rgba(28,28,30,0.6);
    }
    .hero-overlay {
      position: absolute;
      inset: 0;
      background: linear-gradient(to top, var(--primary-deep) 0%, transparent 70%);
    }
    .hero-content {
      position: relative;
      text-align: center;
      color: var(--white);
      max-width: 900px;
      padding: 0 20px;
    }
    .hero h1 {
      font-family: var(--font-title);
      font-size: 3.5rem;
      font-weight: 700;
      letter-spacing: -0.8px;
      line-height: 1.2;
      margin-bottom: 1.5rem;
      text-shadow: 0 4px 20px rgba(0,0,0,0.4);
    }
    .hero-sub {
      font-size: 1.25rem;
      opacity: 0.9;
      margin-bottom: 2.5rem;
      text-shadow: 0 2px 10px rgba(0,0,0,0.5);
    }
    .btn-group {
      display: flex;
      gap: 1.5rem;
      justify-content: center;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--accent-orange);
      color: white;
      padding: 14px 36px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      letter-spacing: 0.5px;
      box-shadow: 0 8px 18px rgba(255,79,0,0.3);
    }
    .btn-primary:hover {
      background: var(--accent-orange-hover);
      transform: scale(1.02);
      box-shadow: 0 12px 24px rgba(255,79,0,0.4);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--accent-orange);
      color: white;
      padding: 12px 34px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: rgba(255,79,0,0.15);
    }
    .scroll-indicator {
      position: absolute;
      bottom: 30px;
      left: 50%;
      transform: translateX(-50%);
      animation: bounce 2s infinite;
      color: white;
      font-size: 2rem;
    }
    @keyframes bounce {
      0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
      40% { transform: translateX(-50%) translateY(-10px); }
      60% { transform: translateX(-50%) translateY(-5px); }
    }
    @media (max-width: 768px) {
      .hero h1 {
        font-size: 2.5rem;
      }
    }

    /* 通用板块 */
    section {
      padding: 90px 0;
    }
    .section-title {
      font-family: var(--font-title);
      font-size: 2.5rem;
      font-weight: 700;
      letter-spacing: -0.5px;
      margin-bottom: 1rem;
    }
    .section-desc {
      color: var(--text-secondary);
      font-size: 1.1rem;
      max-width: 700px;
    }
    .center {
      text-align: center;
      margin-left: auto;
      margin-right: auto;
    }
    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
      .section-title {
        font-size: 2rem;
      }
    }

    /* 优势卡片 */
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .adv-card {
      background: var(--white);
      border-radius: var(--radius-card);
      padding: 32px 24px;
      border: 1px solid var(--border-light);
      transition: var(--transition-smooth);
    }
    .adv-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    .adv-icon {
      font-size: 2.2rem;
      color: var(--accent-orange);
      margin-bottom: 18px;
    }
    @media (max-width: 1024px) {
      .advantages-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 520px) {
      .advantages-grid {
        grid-template-columns: 1fr;
      }
    }

    /* 产品非对称 */
    .product-showcase {
      display: flex;
      flex-wrap: wrap;
      gap: 24px;
      margin-top: 48px;
    }
    .product-large {
      flex: 2 1 65%;
      background: var(--white);
      border-radius: var(--radius-card);
      display: flex;
      flex-direction: column;
      border: 1px solid var(--border-light);
      overflow: hidden;
    }
    .product-small-group {
      flex: 1 1 30%;
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    .product-card {
      background: var(--white);
      border-radius: var(--radius-card);
      border: 1px solid var(--border-light);
      overflow: hidden;
      transition: var(--transition-smooth);
    }
    .product-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card);
    }
    .product-img {
      height: 200px;
      background-size: cover;
      background-position: center;
    }
    .product-info {
      padding: 24px;
    }
    @media (max-width: 768px) {
      .product-showcase {
        flex-direction: column;
      }
    }

    /* 场景交替 */
    .scenario-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-top: 60px;
    }
    .scenario-img {
      flex: 1;
      height: 360px;
      background-size: cover;
      background-position: center;
      border-radius: var(--radius-card);
    }
    .scenario-text {
      flex: 1;
    }
    .tag {
      background: rgba(255,79,0,0.1);
      color: var(--accent-orange);
      padding: 4px 14px;
      border-radius: 20px;
      font-size: 0.9rem;
      display: inline-block;
      margin-bottom: 15px;
    }
    @media (max-width: 768px) {
      .scenario-row {
        flex-direction: column;
        gap: 30px;
      }
    }

    /* 案例数据 */
    .stats-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      margin-top: 48px;
    }
    .big-number {
      font-size: 3.5rem;
      font-weight: 700;
      color: var(--accent-orange);
      line-height: 1;
    }
    .case-card {
      background: var(--white);
      border-left: 4px solid var(--accent-orange);
      padding: 24px;
      border-radius: 0 var(--radius-card) var(--radius-card) 0;
    }
    @media (max-width: 768px) {
      .stats-grid {
        grid-template-columns: 1fr;
      }
    }

    /* FAQ */
    .faq-list {
      margin-top: 40px;
    }
    .faq-item {
      border-bottom: 1px solid var(--silver-light);
      padding: 18px 0;
      cursor: pointer;
    }
    .faq-question {
      font-weight: 700;
      font-size: 1.15rem;
      display: flex;
      justify-content: space-between;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-secondary);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      margin-top: 12px;
    }

    /* CTA */
    .cta-section {
      background: var(--primary-deep);
      color: white;
      text-align: center;
      border-radius: 0;
    }
    .footer {
      background: var(--primary-deep);
      color: var(--text-on-dark);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }