/* roulang page: index */
:root {
      --primary-orange: #FF4E00;
      --primary-deep: #E04400;
      --secondary-yellow: #FFC700;
      --titanium-gray: #1A1C20;
      --bg-light: #F8F9FA;
      --bg-white: #FFFFFF;
      --text-body: #4B5563;
      --text-heading: #111827;
      --text-light: #9CA3AF;
      --border-light: #E5E7EB;
      --radius-sm: 4px;
      --radius-md: 8px;
      --radius-lg: 12px;
      --shadow-card: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -1px rgba(0,0,0,0.03);
      --shadow-hover: 0 20px 25px -5px rgba(0,0,0,0.08), 0 8px 10px -3px rgba(0,0,0,0.03);
      --shadow-button: 2px 2px 0px rgba(0,0,0,0.1);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-digit: "Inter", "DIN Alternate", sans-serif;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      scroll-padding-top: 80px;
    }
    body {
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.7;
      color: var(--text-body);
      background-color: var(--bg-white);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s ease;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: transparent;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 0.5rem;
      font-weight: 600;
      transition: all 0.15s ease;
      border-radius: var(--radius-sm);
    }
    ul {
      list-style: none;
    }
    .container {
      width: 100%;
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }
    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 100;
      background: rgba(26, 28, 32, 0.8);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(255,255,255,0.05);
      transition: background 0.25s ease, box-shadow 0.25s ease;
    }
    .header.scrolled {
      background: var(--titanium-gray);
      box-shadow: 0 6px 20px rgba(0,0,0,0.25);
      backdrop-filter: blur(8px);
    }
    .nav-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .logo {
      display: flex;
      align-items: center;
      font-weight: 800;
      font-size: 1.7rem;
      letter-spacing: -0.5px;
      color: #FFFFFF;
      line-height: 1.2;
    }
    .logo span {
      color: var(--primary-orange);
      font-weight: 900;
    }
    .nav-links {
      display: flex;
      gap: 2.2rem;
      align-items: center;
    }
    .nav-links a {
      color: rgba(255,255,255,0.82);
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      padding: 0.25rem 0;
      letter-spacing: 0.3px;
    }
    .nav-links a::after {
      content: "";
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--primary-orange);
      transition: width 0.2s ease;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: #FFFFFF;
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
    }
    .hamburger span {
      width: 26px;
      height: 2.5px;
      background: white;
      border-radius: 2px;
      transition: 0.2s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: var(--titanium-gray);
      z-index: 99;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 2.5rem;
      transform: translateX(100%);
      transition: transform 0.35s ease;
    }
    .mobile-menu.open {
      transform: translateX(0);
    }
    .mobile-menu a {
      font-size: 1.8rem;
      font-weight: 600;
      color: white;
      letter-spacing: 1px;
    }
    /* 英雄区 */
    .hero {
      min-height: 100vh;
      background: linear-gradient(135deg, rgba(26,28,32,0.7) 0%, rgba(0,0,0,0.6) 100%), url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
    }
    .hero::before {
      content: "";
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 120px;
      background: linear-gradient(to top, var(--titanium-gray), transparent);
   }
    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 750px;
      color: white;
      padding: 2rem 0;
    }
    .hero h1 {
      font-weight: 900;
      font-size: clamp(3rem, 8vw, 5.2rem);
      letter-spacing: -0.02em;
      line-height: 1.1;
      margin-bottom: 1.5rem;
      text-shadow: 0 5px 15px rgba(0,0,0,0.4);
    }
    .hero h1 span {
      color: var(--primary-orange);
    }
    .hero-sub {
      font-size: 1.15rem;
      color: rgba(255,255,255,0.75);
      margin-bottom: 2.5rem;
      max-width: 500px;
      line-height: 1.6;
    }
    .btn-primary {
      background: var(--primary-orange);
      color: white;
      padding: 0.9rem 2.5rem;
      font-size: 1.05rem;
      font-weight: 700;
      border-radius: var(--radius-sm);
      box-shadow: var(--shadow-button);
      transition: 0.15s;
      letter-spacing: 0.5px;
    }
    .btn-primary:hover {
      background: var(--primary-deep);
      transform: translate(2px, 2px);
      box-shadow: none;
    }
    .btn-outline {
      border: 2px solid var(--primary-orange);
      color: var(--primary-orange);
      background: transparent;
      padding: 0.8rem 2.2rem;
      font-weight: 700;
      border-radius: var(--radius-sm);
    }
    .btn-outline:hover {
      background: rgba(255,78,0,0.08);
    }
    .btn-white {
      background: white;
      color: var(--titanium-gray);
      font-weight: 700;
      padding: 0.9rem 2.5rem;
      border-radius: var(--radius-sm);
    }
    /* 板块通用 */
    section {
      padding: 5rem 0;
    }
    .section-title {
      font-weight: 700;
      font-size: clamp(2rem, 5vw, 2.8rem);
      margin-bottom: 1rem;
      color: var(--text-heading);
    }
    .section-desc {
      color: #6B7280;
      max-width: 600px;
      margin-bottom: 3rem;
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .card {
      background: var(--bg-white);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 2rem;
      box-shadow: var(--shadow-card);
      transition: all 0.25s;
    }
    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
      border-color: var(--primary-orange);
    }
    .icon-orange {
      color: var(--primary-orange);
      font-size: 2.2rem;
      margin-bottom: 1.25rem;
    }
    .card h3 {
      font-weight: 600;
      font-size: 1.3rem;
      margin-bottom: 0.75rem;
      color: #1F2937;
    }
    /* 案例与场景 */
    .bg-dark {
      background: var(--titanium-gray);
      color: white;
    }
    .stat-highlight {
      color: var(--secondary-yellow);
      font-family: var(--font-digit);
      font-weight: 700;
      font-size: 2.4rem;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1.2rem 0;
    }
    .faq-question {
      font-weight: 600;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 2rem;
    }
    @media (max-width: 1024px) {
      .grid-3 { grid-template-columns: repeat(2, 1fr); }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .grid-3 { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      .hero h1 { font-size: 2.8rem; }
    }