/* roulang page: index */
:root {
      --primary-red: #E60012;
      --deep-black: #1A1A1A;
      --titanium-gray: #F0F2F5;
      --vibrant-orange: #FF6B00;
      --pure-white: #FFFFFF;
      --soft-bg: #F8F9FA;
      --text-main: #1A1A1A;
      --text-secondary: #5A5A5A;
      --text-light: #8A8A8A;
      --border-light: #E5E7EB;
      --shadow-sm: 0 4px 20px rgba(0, 0, 0, 0.04);
      --shadow-md: 0 12px 32px rgba(0, 0, 0, 0.08);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition: 0.25s ease-in-out;
      --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --nav-width: 80px;
      --header-height-mobile: 64px;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--pure-white);
      color: var(--text-main);
      line-height: 1.6;
      margin: 0;
      padding: 0;
      overflow-x: hidden;
      -webkit-font-smoothing: antialiased;
    }

    h1, h2, h3, h4, h5, h6 {
      font-weight: 700;
      letter-spacing: -0.02em;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }

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

    /* 左侧竖向导航 (桌面) */
    .vertical-nav {
      position: fixed;
      left: 0;
      top: 0;
      width: var(--nav-width);
      height: 100vh;
      background-color: var(--deep-black);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: flex-start;
      padding: 2rem 0;
      z-index: 1050;
      box-shadow: 2px 0 12px rgba(0,0,0,0.08);
      transition: var(--transition);
    }

    .nav-logo {
      margin-bottom: 2.5rem;
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--pure-white);
      writing-mode: vertical-rl;
      text-orientation: mixed;
      letter-spacing: 4px;
      line-height: 1.2;
      cursor: pointer;
    }
    .nav-logo span {
      display: block;
      color: var(--primary-red);
    }

    .nav-menu {
      display: flex;
      flex-direction: column;
      gap: 2rem;
      list-style: none;
      padding: 0;
      margin: 0;
    }

    .nav-item a {
      display: flex;
      flex-direction: column;
      align-items: center;
      color: #B0B0B0;
      font-size: 0.75rem;
      font-weight: 500;
      transition: var(--transition);
      padding: 0.5rem 0;
      border-radius: 8px;
      width: 60px;
      text-align: center;
    }

    .nav-item a i {
      font-size: 1.4rem;
      margin-bottom: 0.25rem;
      transition: var(--transition);
    }

    .nav-item a:hover,
    .nav-item a.active {
      color: var(--primary-red);
      transform: translateX(4px);
    }

    /* 移动端顶部导航 */
    .mobile-header {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height-mobile);
      background-color: var(--deep-black);
      z-index: 1040;
      align-items: center;
      justify-content: space-between;
      padding: 0 1.5rem;
      box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    }

    .mobile-logo {
      font-size: 1.4rem;
      font-weight: 700;
      color: white;
    }
    .mobile-logo span {
      color: var(--primary-red);
    }

    .hamburger {
      color: white;
      font-size: 1.8rem;
      cursor: pointer;
    }

    .mobile-menu {
      position: fixed;
      top: var(--header-height-mobile);
      left: 0;
      width: 100%;
      background: var(--deep-black);
      flex-direction: column;
      padding: 1.5rem;
      display: none;
      z-index: 1030;
    }

    .mobile-menu.show {
      display: flex;
    }

    .mobile-menu a {
      color: #ccc;
      padding: 0.8rem 0;
      border-bottom: 1px solid #333;
      font-weight: 500;
    }

    /* 主内容区域 */
    .main-content {
      margin-left: var(--nav-width);
      width: calc(100% - var(--nav-width));
      transition: margin-left 0.2s;
    }

    section {
      padding: 100px 0;
    }

    .section-title h2 {
      font-size: 2.5rem;
      font-weight: 700;
      margin-bottom: 1rem;
      color: var(--deep-black);
    }
    .section-title .divider {
      width: 60px;
      height: 4px;
      background: var(--primary-red);
      margin: 1rem 0 2rem;
    }

    /* Hero */
    .hero-section {
      height: 100vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, rgba(230,0,18,0.08) 0%, rgba(26,26,26,0.85) 70%), url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      color: white;
      position: relative;
    }
    .hero-content h1 {
      font-size: 3.8rem;
      font-weight: 700;
      line-height: 1.2;
      text-shadow: 0 4px 20px rgba(0,0,0,0.5);
    }
    .hero-content .lead {
      font-size: 1.3rem;
      opacity: 0.9;
      margin: 1.5rem 0 2rem;
    }

    .btn-primary-red {
      background: var(--primary-red);
      border: none;
      color: white;
      padding: 0.75rem 2.2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: var(--transition);
    }
    .btn-primary-red:hover {
      background: #c4000f;
      transform: scale(1.03);
      color: white;
    }
    .btn-outline-white {
      border: 2px solid white;
      color: white;
      padding: 0.75rem 2.2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      background: transparent;
    }
    .btn-outline-white:hover {
      background: white;
      color: var(--deep-black);
    }

    /* 卡片通用 */
    .custom-card {
      background: white;
      border-radius: var(--radius-card);
      padding: 2rem;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      height: 100%;
      border: 1px solid var(--border-light);
    }
    .custom-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }

    .stat-number {
      font-size: 2.8rem;
      font-weight: 700;
      color: var(--vibrant-orange);
      line-height: 1.2;
    }

    .testimonial-card {
      background: var(--titanium-gray);
      border-radius: var(--radius-card);
      padding: 2rem;
      position: relative;
    }
    .testimonial-card::before {
      content: "“";
      font-size: 4rem;
      color: var(--primary-red);
      position: absolute;
      top: -10px;
      left: 20px;
      opacity: 0.3;
    }

    .accordion-button:not(.collapsed) {
      background-color: transparent;
      color: var(--primary-red);
      font-weight: 600;
      box-shadow: none;
    }
    .accordion-button:focus {
      border-color: var(--primary-red);
      box-shadow: 0 0 0 0.2rem rgba(230,0,18,0.15);
    }

    footer {
      background: var(--deep-black);
      color: #ccc;
    }

    @media (max-width: 992px) {
      .vertical-nav {
        display: none;
      }
      .mobile-header {
        display: flex;
      }
      .main-content {
        margin-left: 0;
        width: 100%;
        padding-top: var(--header-height-mobile);
      }
      .hero-section {
        height: auto;
        padding: 140px 0 80px;
      }
      .hero-content h1 {
        font-size: 2.8rem;
      }
    }

    @media (max-width: 768px) {
      section {
        padding: 70px 0;
      }
      .hero-content h1 {
        font-size: 2.2rem;
      }
      .section-title h2 {
        font-size: 2rem;
      }
    }