/* roulang page: index */
/* ----- 设计变量与基础重置 ----- */
    :root {
      --primary-charcoal: #2B2418;
      --accent-gold: #C49A2B;
      --bg-warm-linen: #F7F4EF;
      --bg-light: #FAF8F5;
      --deep-terracotta: #8B3A3A;
      --white: #FFFFFF;
      --border-soft: #E8E3DA;
      --text-body: #2B2418;
      --text-muted: rgba(43, 36, 24, 0.7);
      --text-light-on-dark: #F7F4EF;
      --radius-sm: 6px;
      --shadow-sm: 0 2px 12px rgba(43, 36, 24, 0.04);
      --shadow-md: 0 8px 28px rgba(43, 36, 24, 0.08);
      --transition-smooth: 0.3s cubic-bezier(0.25, 0.8, 0.25, 1.2);
      --font-serif: 'Noto Serif SC', 'Times New Roman', serif;
      --font-sans: 'Inter', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
      --max-width: 1280px;
      --section-gap-desktop: 120px;
      --section-gap-tablet: 80px;
      --section-gap-mobile: 60px;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-warm-linen);
      color: var(--text-body);
      line-height: 1.7;
      font-size: 17px;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    h1, h2, h3, h4 {
      font-family: var(--font-serif);
      font-weight: 700;
      letter-spacing: -0.5px;
      color: var(--primary-charcoal);
    }

    h1 { font-size: 48px; line-height: 1.2; }
    h2 { font-size: 36px; line-height: 1.25; margin-bottom: 0.8rem; }
    h3 { font-size: 22px; line-height: 1.4; }
    h4 { font-size: 18px; line-height: 1.5; }

    a {
      color: var(--primary-charcoal);
      text-decoration: none;
      transition: color 0.25s ease;
    }

    a:hover {
      color: var(--accent-gold);
    }

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

    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 留白与区块 */
    section {
      padding: var(--section-gap-desktop) 0;
    }

    .section-title {
      text-align: center;
      margin-bottom: 3.5rem;
    }

    .section-title h2 {
      display: inline-block;
      position: relative;
    }

    /* 按钮系统 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-family: var(--font-sans);
      font-weight: 600;
      font-size: 16px;
      padding: 14px 36px;
      border-radius: var(--radius-sm);
      transition: background 0.25s ease, color 0.25s ease, transform 0.2s ease, box-shadow 0.25s ease;
      cursor: pointer;
      border: 1.5px solid transparent;
      line-height: 1.2;
      text-decoration: none;
    }

    .btn-primary {
      background: var(--primary-charcoal);
      color: var(--text-light-on-dark);
      border-color: var(--primary-charcoal);
    }

    .btn-primary:hover {
      background: var(--accent-gold);
      color: var(--primary-charcoal);
      border-color: var(--accent-gold);
      transform: scale(1.02);
      box-shadow: 0 6px 18px rgba(196, 154, 43, 0.25);
    }

    .btn-outline {
      background: transparent;
      color: var(--accent-gold);
      border-color: var(--accent-gold);
    }

    .btn-outline:hover {
      background: rgba(196, 154, 43, 0.1);
      color: var(--primary-charcoal);
      border-color: var(--accent-gold);
      transform: scale(1.02);
    }

    .btn-sm {
      padding: 10px 24px;
      font-size: 15px;
    }

    /* 卡片基础 */
    .card {
      background: var(--white);
      border: 1px solid var(--border-soft);
      border-radius: var(--radius-sm);
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.3s ease, transform 0.3s ease;
      overflow: hidden;
    }

    .card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-2px);
    }

    /* 顶部信息条 */
    .top-bar-strip {
      background: var(--primary-charcoal);
      color: var(--text-light-on-dark);
      font-size: 12px;
      letter-spacing: 0.5px;
      height: 36px;
      line-height: 36px;
      padding: 0 24px;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .top-bar-strip a {
      color: var(--text-light-on-dark);
      margin-left: 2rem;
    }

    /* 主导航 */
    .main-nav {
      background: var(--bg-warm-linen);
      height: 72px;
      display: flex;
      align-items: center;
      border-bottom: 1px solid rgba(0,0,0,0.05);
    }

    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .brand {
      font-family: var(--font-serif);
      font-size: 24px;
      font-weight: 700;
      color: var(--primary-charcoal);
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .brand-icon {
      width: 28px;
      height: 28px;
      position: relative;
    }

    .brand-icon svg {
      width: 100%;
      height: 100%;
    }

    .nav-links {
      display: flex;
      gap: 2.5rem;
      list-style: none;
      margin: 0;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--primary-charcoal);
      position: relative;
      padding: 4px 0;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: 0;
      width: 0;
      height: 2px;
      background: var(--accent-gold);
      transition: width 0.25s ease;
    }

    .nav-links a:hover::after {
      width: 100%;
    }

    .hamburger {
      display: none;
      flex-direction: column;
      cursor: pointer;
      gap: 5px;
    }

    .hamburger span {
      width: 25px;
      height: 2px;
      background: var(--primary-charcoal);
      display: block;
    }

    /* 移动端导航遮罩 */
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0; left: 0; width: 100%; height: 100%;
      background: var(--bg-warm-linen);
      z-index: 999;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      gap: 2rem;
      font-size: 20px;
    }

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

    .close-menu {
      position: absolute;
      top: 24px; right: 24px;
      font-size: 32px;
      cursor: pointer;
    }

    /* Hero双栏 */
    .hero-grid {
      display: flex;
      gap: 60px;
      align-items: center;
    }

    .hero-left {
      flex: 0 0 55%;
    }

    .hero-right {
      flex: 0 0 45%;
    }

    .hero-image {
      border-radius: var(--radius-sm);
      border: 1px solid var(--border-soft);
      overflow: hidden;
    }

    .hero-image img {
      width: 100%;
      height: auto;
      aspect-ratio: 4 / 3;
      object-fit: cover;
      transition: transform 0.4s ease;
    }

    .hero-image:hover img {
      transform: scale(1.03);
    }

    .hero-subtitle {
      font-size: 18px;
      line-height: 1.7;
      color: var(--text-muted);
      margin: 1.5rem 0 2rem;
    }

    /* 非对称网格 */
    .asymmetric-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
    }

    .grid-item-large {
      grid-column: span 2;
    }

    .strength-card {
      padding: 36px;
      background: var(--white);
      border: 1px solid var(--border-soft);
      border-radius: var(--radius-sm);
    }

    .strength-card.large {
      display: flex;
      gap: 2rem;
    }

    .accent-line {
      width: 2px;
      height: 60px;
      background: var(--accent-gold);
      flex-shrink: 0;
    }

    .icon-placeholder {
      font-size: 40px;
      color: var(--accent-gold);
      margin-bottom: 1rem;
    }

    /* 瀑布流 */
    .masonry {
      columns: 3;
      column-gap: 28px;
    }

    .masonry-item {
      break-inside: avoid;
      margin-bottom: 28px;
      background: var(--white);
      border-bottom: 1px solid var(--border-soft);
      transition: box-shadow 0.3s;
    }

    .masonry-item:hover {
      box-shadow: var(--shadow-md);
    }

    .masonry-item img {
      width: 100%;
      height: auto;
      transition: transform 0.4s ease;
    }

    .masonry-item:hover img {
      transform: scale(1.03);
    }

    .masonry-content {
      padding: 1.2rem 1rem 1.5rem;
    }

    .tag {
      background: rgba(43,36,24,0.08);
      color: var(--primary-charcoal);
      padding: 4px 10px;
      border-radius: 4px;
      font-size: 13px;
    }

    /* 对比表 */
    .compare-table {
      width: 100%;
      border-collapse: collapse;
      background: var(--white);
      border-radius: var(--radius-sm);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }

    .compare-table th {
      background: var(--primary-charcoal);
      color: var(--text-light-on-dark);
      padding: 16px;
      font-weight: 600;
    }

    .compare-table td {
      padding: 16px;
      border-bottom: 1px solid var(--border-soft);
    }

    .compare-table tr:nth-child(even) td {
      background: var(--bg-warm-linen);
    }

    .highlight-col {
      border-left: 3px solid var(--accent-gold);
    }

    /* FAQ */
    .accordion-faq {
      max-width: 800px;
      margin: 0 auto;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-soft);
      padding: 1rem 0;
    }

    .faq-question {
      font-weight: 600;
      font-size: 18px;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 12px;
      transition: color 0.2s;
    }

    .faq-question:hover {
      color: var(--accent-gold);
    }

    .faq-dot {
      width: 6px; height: 6px;
      background: var(--accent-gold);
      border-radius: 50%;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-muted);
      margin-top: 0.5rem;
      padding-left: 18px;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
    }

    /* 联系表单 */
    .contact-wrapper {
      background: var(--bg-light);
      border-radius: var(--radius-sm);
      padding: 3rem;
    }

    .input-line {
      border: none;
      border-bottom: 1px solid var(--border-soft);
      background: transparent;
      padding: 10px 0;
      width: 100%;
      font-size: 16px;
      transition: border-color 0.2s;
    }

    .input-line:focus {
      outline: none;
      border-bottom: 2px solid var(--accent-gold);
    }

    /* 页脚 */
    .footer {
      background: var(--primary-charcoal);
      color: var(--text-light-on-dark);
      padding: 3rem 0 1.5rem;
    }

    .footer a {
      color: var(--text-light-on-dark);
    }

    .footer a:hover {
      color: var(--accent-gold);
    }

    /* 滚动动画 */
    .reveal-on-scroll {
      opacity: 0;
      transform: translateY(12px);
      transition: opacity 0.6s ease, transform 0.6s ease;
    }

    .revealed {
      opacity: 1;
      transform: translateY(0);
    }

    @media (max-width: 1024px) {
      h1 { font-size: 40px; }
      .hero-grid { gap: 32px; }
      .asymmetric-grid { grid-template-columns: repeat(2, 1fr); }
      .grid-item-large { grid-column: span 2; }
      .masonry { columns: 2; }
    }

    @media (max-width: 768px) {
      section { padding: var(--section-gap-tablet) 0; }
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .hero-grid { flex-direction: column; }
      .hero-left, .hero-right { flex: auto; width: 100%; }
      .asymmetric-grid { grid-template-columns: 1fr; }
      .grid-item-large { grid-column: span 1; }
      .masonry { columns: 1; }
    }

    @media (max-width: 520px) {
      section { padding: var(--section-gap-mobile) 0; }
      h1 { font-size: 34px; }
      .compare-table-wrapper { overflow-x: auto; }
      .btn { padding: 12px 24px; }
    }