/* roulang page: index */
:root {
      --bg-dark: #0F0F0F;
      --bg-charcoal: #1A1A1A;
      --bg-paper: #F5F3EF;
      --white: #FFFFFF;
      --text-primary: #1A1A1A;
      --text-secondary: #8A8A8A;
      --accent-amber: #C87A3C;
      --accent-amber-hover: #A8632A;
      --accent-amber-light: rgba(200, 122, 60, 0.08);
      --border-light: #E0E0E0;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-hover: 0 4px 20px rgba(0,0,0,0.08);
      --radius-sm: 2px;
      --radius-card: 4px;
      --font-serif: 'Noto Serif SC', 'Source Han Serif', serif;
      --font-sans: 'Noto Sans SC', 'Inter', sans-serif;
      --font-number: 'Inter', 'SF Pro Display', sans-serif;
      --max-width: 1280px;
      --nav-height: 72px;
      --mobile-tab-height: 56px;
      --section-gap: 120px;
      --section-gap-mobile: 80px;
      --card-padding: 32px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-dark);
      color: var(--text-primary);
      line-height: 1.7;
      font-weight: 300;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
      padding-bottom: var(--mobile-tab-height);
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    /* 背景装饰纹理 */
    .bg-texture {
      background-color: var(--bg-charcoal);
      background-image: radial-gradient(rgba(255,255,255,0.03) 1px, transparent 1px);
      background-size: 24px 24px;
    }
    .bg-paper {
      background-color: var(--bg-paper);
    }
    /* 排版 */
    h1, h2, h3 {
      font-family: var(--font-serif);
      font-weight: 700;
      letter-spacing: -0.3px;
    }
    h1 {
      font-size: 2.5rem;
      line-height: 1.3;
      color: var(--white);
    }
    h2 {
      font-size: 1.8rem;
      margin-bottom: 1.5rem;
      color: var(--text-primary);
    }
    h3 {
      font-size: 1.25rem;
      font-weight: 600;
      margin-bottom: 0.75rem;
    }
    p {
      color: var(--text-secondary);
      font-size: 0.95rem;
      max-width: 600px;
    }
    .section-padding {
      padding: var(--section-gap) 0;
    }
    .bg-dark-section {
      background-color: var(--bg-charcoal);
    }
    .text-white {
      color: var(--white);
    }
    .text-secondary {
      color: var(--text-secondary);
    }
    /* 按钮 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 500;
      font-size: 0.95rem;
      text-decoration: none;
      transition: all 0.25s ease;
      cursor: pointer;
      border: 1px solid transparent;
      letter-spacing: 0.3px;
    }
    .btn-primary {
      background-color: var(--accent-amber);
      color: var(--white);
      border-color: var(--accent-amber);
    }
    .btn-primary:hover {
      background-color: var(--accent-amber-hover);
      border-color: var(--accent-amber-hover);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--accent-amber);
      color: var(--accent-amber);
    }
    .btn-outline:hover {
      background-color: var(--accent-amber-light);
    }
    .btn-light {
      background: transparent;
      border: 1px solid var(--white);
      color: var(--white);
    }
    .btn-light:hover {
      background-color: rgba(255,255,255,0.08);
    }
    /* 导航 */
    .main-nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      z-index: 100;
      background: transparent;
      transition: background 0.3s ease, backdrop-filter 0.3s ease;
      display: flex;
      align-items: center;
    }
    .main-nav.scrolled {
      background: rgba(15, 15, 15, 0.85);
      backdrop-filter: blur(12px);
      box-shadow: 0 2px 8px rgba(0,0,0,0.2);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      display: flex;
      flex-direction: column;
      line-height: 1.2;
    }
    .logo-main {
      font-family: var(--font-serif);
      font-weight: 700;
      font-size: 1.4rem;
      color: var(--white);
      letter-spacing: 1px;
    }
    .logo-domain {
      font-size: 0.7rem;
      color: var(--text-secondary);
      font-weight: 300;
    }
    .desktop-menu {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .desktop-menu a {
      color: var(--white);
      text-decoration: none;
      font-size: 0.9rem;
      font-weight: 400;
      transition: color 0.2s;
      padding: 0.25rem 0;
      border-bottom: 1px solid transparent;
    }
    .desktop-menu a:hover {
      color: var(--accent-amber);
    }
    .lang-switch {
      color: var(--text-secondary);
      font-size: 0.8rem;
      margin-left: 1rem;
      cursor: default;
    }
    .hamburger {
      display: none;
      background: none;
      border: none;
      color: var(--white);
      font-size: 1.5rem;
      cursor: pointer;
    }
    /* 移动底部Tab */
    .mobile-tab-bar {
      display: none;
      position: fixed;
      bottom: 0;
      left: 0;
      width: 100%;
      height: var(--mobile-tab-height);
      background: rgba(15, 15, 15, 0.95);
      backdrop-filter: blur(10px);
      border-top: 1px solid rgba(255,255,255,0.08);
      z-index: 110;
      justify-content: space-around;
      align-items: center;
      padding: 0 8px;
    }
    .tab-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      color: var(--text-secondary);
      text-decoration: none;
      font-size: 10px;
      font-weight: 400;
      transition: color 0.2s;
      gap: 4px;
    }
    .tab-item i {
      font-size: 1.2rem;
    }
    .tab-item.active {
      color: var(--accent-amber);
    }
    /* 板块动画 */
    .fade-in-section {
      opacity: 0;
      transform: translateY(20px);
      transition: opacity 0.6s ease, transform 0.6s ease;
    }
    .fade-in-section.visible {
      opacity: 1;
      transform: translateY(0);
    }
    /* Hero */
    .hero-grid {
      display: grid;
      grid-template-columns: 55% 45%;
      min-height: 100vh;
      align-items: center;
      padding-top: var(--nav-height);
    }
    .hero-abstract {
      position: relative;
      width: 100%;
      height: 350px;
      background: radial-gradient(circle at 30% 40%, rgba(200,122,60,0.15) 0%, transparent 60%);
      display: flex;
      align-items: center;
      justify-content: center;
    }
    .abstract-lines {
      width: 100%;
      height: 100%;
      background: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 200"><path d="M30 170 L90 30 L150 150 L170 40" fill="none" stroke="%23C87A3C" stroke-width="1.2" opacity="0.4"/><path d="M20 130 L110 110 L160 70" fill="none" stroke="%23C87A3C" stroke-width="0.8" opacity="0.25"/></svg>') no-repeat center;
      background-size: contain;
    }
    /* 痛点 */
    .pain-item {
      display: flex;
      align-items: flex-start;
      gap: 1.5rem;
      margin-bottom: 2.5rem;
    }
    .pain-indicator {
      width: 2px;
      min-width: 2px;
      height: 28px;
      background-color: var(--accent-amber);
      margin-top: 0.3rem;
    }
    /* 解决方案交替布局 */
    .solution-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 3rem;
      align-items: center;
      margin-bottom: 5rem;
    }
    .solution-row.reverse .solution-text {
      order: 2;
    }
    .solution-row.reverse .solution-img {
      order: 1;
    }
    .solution-img {
      background-color: #EAE6E0;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      height: 260px;
      position: relative;
    }
    .solution-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      filter: grayscale(30%);
      transition: transform 0.4s;
    }
    .solution-img:hover img {
      transform: scale(1.02);
    }
    .solution-img::after {
      content: '';
      position: absolute;
      top: 0; left: 0; right: 0; bottom: 0;
      background: rgba(200,122,60,0.12);
    }
    /* 数据仪表盘 */
    .metrics-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      gap: 1rem;
    }
    .metric-value {
      font-family: var(--font-number);
      font-size: 2.8rem;
      font-weight: 700;
      color: var(--text-primary);
      line-height: 1.2;
    }
    .metric-label {
      font-size: 0.9rem;
      color: var(--text-secondary);
      margin-top: 0.5rem;
    }
    .metric-divider {
      width: 1px;
      height: 40px;
      background: #E0E0E0;
      margin: 0 auto;
    }
    /* 证言 */
    .testimonial-block {
      position: relative;
      padding-left: 2rem;
      margin-bottom: 2.5rem;
    }
    .testimonial-quote {
      font-size: 1.3rem;
      font-style: italic;
      color: var(--text-primary);
      margin-bottom: 1rem;
      line-height: 1.6;
    }
    .testimonial-author {
      font-weight: 600;
      font-size: 0.95rem;
    }
    .testimonial-role {
      color: var(--text-secondary);
      font-size: 0.8rem;
    }
    /* CTA */
    .cta-section {
      background-color: var(--bg-charcoal);
      text-align: center;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
    }
    .footer-bottom {
      border-top: 1px solid rgba(255,255,255,0.1);
      margin-top: 2rem;
      padding-top: 1.5rem;
      display: flex;
      justify-content: space-between;
      font-size: 0.8rem;
      color: var(--text-secondary);
    }
    @media (max-width: 1024px) {
      .hero-grid { grid-template-columns: 1fr; text-align: center; }
      .hero-abstract { height: 250px; margin-top: 2rem; }
      .metrics-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 768px) {
      .desktop-menu { display: none; }
      .hamburger { display: block; }
      .mobile-tab-bar { display: flex; }
      body { padding-bottom: var(--mobile-tab-height); }
      .section-padding { padding: var(--section-gap-mobile) 0; }
      h1 { font-size: 2rem; }
      .solution-row { grid-template-columns: 1fr; gap: 1.5rem; }
      .solution-row.reverse .solution-text { order: 1; }
      .solution-row.reverse .solution-img { order: 1; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
      .metrics-grid { grid-template-columns: 1fr 1fr; }
      .metric-value { font-size: 2.2rem; }
    }
    @media (max-width: 520px) {
      .footer-grid { grid-template-columns: 1fr; }
    }