/* roulang page: index */
/* 基础设计变量与CSS Reset */
    :root {
      --primary-red: #E63946;
      --primary-red-dark: #C1121F;
      --accent-green: #A7C957;
      --accent-green-glow: #BADC58;
      --deep-black: #1A1A1A;
      --soft-white: #FDFBF7;
      --pure-white: #FFFFFF;
      --mid-gray: #4A4A4A;
      --light-gray: #E5E5E5;
      --border-light: rgba(0,0,0,0.06);
      
      --font-sans: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
      --font-number: 'Inter', 'Roboto', sans-serif;
      
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 20px;
      
      --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.04);
      --shadow-card-hover: 0 12px 32px rgba(0, 0, 0, 0.08);
      --shadow-nav: 0 2px 12px rgba(0, 0, 0, 0.04);
      
      --transition-smooth: all 0.25s cubic-bezier(0.25, 0.8, 0.25, 1);
      --max-width: 1200px;
    }
    
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    
    body {
      font-family: var(--font-sans);
      background-color: var(--soft-white);
      color: var(--deep-black);
      line-height: 1.5;
      overflow-x: hidden;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition-smooth);
    }
    
    button, .btn {
      cursor: pointer;
      font-family: var(--font-sans);
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-weight: 700;
      letter-spacing: 0.05em;
      transition: var(--transition-smooth);
      border-radius: var(--radius-sm);
      white-space: nowrap;
    }
    
    ul {
      list-style: none;
    }
    
    .container {
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    
    /* 排版通用 */
    h1, h2, h3, h4 {
      font-weight: 700;
      line-height: 1.25;
    }
    
    .section-title {
      font-size: clamp(2.2rem, 5vw, 3.2rem);
      letter-spacing: -0.02em;
      margin-bottom: 1rem;
      color: var(--deep-black);
    }
    
    .section-subtitle {
      font-size: 1.1rem;
      color: var(--mid-gray);
      max-width: 650px;
      margin: 0 auto 3rem auto;
      line-height: 1.7;
    }
    
    /* 导航样式 */
    .main-header {
      position: sticky;
      top: 0;
      z-index: 1000;
      background: rgba(253, 251, 247, 0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-light);
      box-shadow: var(--shadow-nav);
    }
    
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    
    .logo-area {
      display: flex;
      align-items: center;
      gap: 10px;
      font-weight: 900;
      font-size: 1.4rem;
      letter-spacing: -0.02em;
      color: var(--deep-black);
    }
    
    .logo-icon {
      font-size: 2rem;
      color: var(--primary-red);
    }
    
    .logo-text {
      display: flex;
      flex-direction: column;
      line-height: 1.2;
    }
    
    .logo-text small {
      font-size: 0.7rem;
      font-weight: 500;
      color: var(--mid-gray);
      letter-spacing: 0.02em;
    }
    
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    
    .nav-link {
      font-weight: 500;
      color: var(--mid-gray);
      position: relative;
      padding: 4px 0;
      font-size: 0.95rem;
    }
    
    .nav-link:hover,
    .nav-link.active {
      color: var(--primary-red);
    }
    
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary-red);
      transition: width 0.2s ease;
    }
    
    .nav-link:hover::after,
    .nav-link.active::after {
      width: 100%;
    }
    
    .btn-primary {
      background: var(--primary-red);
      color: white;
      padding: 12px 28px;
      font-weight: 700;
      box-shadow: 0 4px 12px rgba(230, 57, 70, 0.3);
    }
    
    .btn-primary:hover {
      background: var(--primary-red-dark);
      transform: translateY(-2px);
      box-shadow: 0 8px 18px rgba(230, 57, 70, 0.4);
    }
    
    .btn-outline {
      background: transparent;
      border: 2px solid var(--deep-black);
      color: var(--deep-black);
      padding: 10px 26px;
    }
    
    .btn-outline:hover {
      background: var(--deep-black);
      color: white;
      transform: translateY(-2px);
    }
    
    .btn-large {
      padding: 16px 40px;
      font-size: 1.1rem;
      border-radius: var(--radius-md);
    }
    
    .hamburger {
      display: none;
      font-size: 1.8rem;
      color: var(--deep-black);
      background: none;
      border: none;
      cursor: pointer;
    }
    
    /* Hero 区域 */
    .hero-section {
      padding: 5rem 0 6rem;
      background: linear-gradient(135deg, #FDFBF7 0%, #F9F5EC 100%);
      position: relative;
      overflow: hidden;
    }
    
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      align-items: center;
    }
    
    .hero-content {
      z-index: 2;
    }
    
    .hero-badge {
      display: inline-block;
      background: rgba(167, 201, 87, 0.15);
      color: #2E4A1C;
      font-weight: 600;
      font-size: 0.9rem;
      padding: 8px 18px;
      border-radius: 30px;
      margin-bottom: 1.5rem;
      letter-spacing: 0.03em;
    }
    
    .hero-title {
      font-weight: 900;
      font-size: clamp(3rem, 8vw, 5.5rem);
      letter-spacing: -0.03em;
      line-height: 1.1;
      color: var(--deep-black);
      margin-bottom: 1.5rem;
    }
    
    .hero-title span {
      color: var(--primary-red);
    }
    
    .hero-desc {
      font-size: 1.2rem;
      color: var(--mid-gray);
      margin-bottom: 2.5rem;
      max-width: 500px;
      line-height: 1.7;
    }
    
    .hero-buttons {
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
    }
    
    .hero-visual {
      position: relative;
      display: flex;
      justify-content: center;
      align-items: center;
    }
    
    .hero-image-wrapper {
      position: relative;
      width: 100%;
      max-width: 500px;
      animation: float 6s ease-in-out infinite;
    }
    
    .hero-image-wrapper img {
      border-radius: var(--radius-lg);
      box-shadow: 0 25px 50px -12px rgba(0,0,0,0.25);
      border: 1px solid rgba(255,255,255,0.5);
    }
    
    .hero-glow {
      position: absolute;
      width: 300px;
      height: 300px;
      background: radial-gradient(circle, rgba(230,57,70,0.2) 0%, transparent 70%);
      top: -20px;
      right: -20px;
      z-index: 0;
      border-radius: 50%;
    }
    
    @keyframes float {
      0% { transform: translateY(0px); }
      50% { transform: translateY(-12px); }
      100% { transform: translateY(0px); }
    }
    
    /* 核心优势卡片 */
    .advantages-section {
      padding: 7rem 0;
      background: var(--pure-white);
    }
    
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    
    .adv-card {
      background: var(--pure-white);
      padding: 2.5rem 2rem;
      border-radius: var(--radius-sm);
      box-shadow: var(--shadow-card);
      transition: var(--transition-smooth);
      border-top: 3px solid transparent;
      text-align: center;
    }
    
    .adv-card:hover {
      border-top-color: var(--primary-red);
      box-shadow: var(--shadow-card-hover);
      transform: translateY(-5px);
    }
    
    .adv-icon {
      font-size: 2.8rem;
      color: var(--primary-red);
      margin-bottom: 1.5rem;
    }
    
    .adv-card h3 {
      font-size: 1.4rem;
      margin-bottom: 1rem;
    }
    
    /* 功能分组交互区 */
    .features-section {
      padding: 7rem 0;
      background: var(--soft-white);
    }
    
    .features-layout {
      display: flex;
      gap: 40px;
      margin-top: 2rem;
    }
    
    .feature-tabs {
      flex: 0 0 260px;
      display: flex;
      flex-direction: column;
      gap: 8px;
    }
    
    .tab-btn {
      text-align: left;
      padding: 18px 24px;
      background: transparent;
      font-weight: 600;
      font-size: 1.05rem;
      color: var(--mid-gray);
      border-radius: var(--radius-sm);
      transition: var(--transition-smooth);
      border-left: 3px solid transparent;
      background: white;
      box-shadow: 0 2px 8px rgba(0,0,0,0.02);
    }
    
    .tab-btn i {
      margin-right: 10px;
      color: var(--primary-red);
    }
    
    .tab-btn.active {
      background: var(--deep-black);
      color: white;
      border-left-color: var(--accent-green);
    }
    
    .tab-btn.active i {
      color: var(--accent-green);
    }
    
    .feature-content {
      flex: 1;
      background: white;
      border-radius: var(--radius-md);
      padding: 2.5rem;
      box-shadow: var(--shadow-card);
      display: flex;
      gap: 30px;
      align-items: center;
      transition: opacity 0.2s ease;
    }
    
    .feature-text h3 {
      font-size: 1.8rem;
      margin-bottom: 1rem;
    }
    
    .feature-text p {
      color: var(--mid-gray);
    }
    
    .feature-img {
      max-width: 220px;
      border-radius: var(--radius-sm);
    }
    
    /* 使用场景网格 */
    .usecase-section {
      padding: 7rem 0;
      background: var(--pure-white);
    }
    
    .usecase-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
    }
    
    .usecase-card {
      background: #F9F9F6;
      border-radius: var(--radius-md);
      padding: 2rem;
      display: flex;
      align-items: center;
      gap: 24px;
      transition: var(--transition-smooth);
    }
    
    .usecase-card:hover {
      background: white;
      box-shadow: var(--shadow-card-hover);
    }
    
    .usecase-icon {
      font-size: 2.5rem;
      color: var(--primary-red);
      width: 70px;
      text-align: center;
    }
    
    /* 数据背书 */
    .proof-section {
      padding: 5rem 0;
      background: var(--deep-black);
      color: white;
    }
    
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 30px;
      text-align: center;
    }
    
    .stat-number {
      font-family: var(--font-number);
      font-size: 3rem;
      font-weight: 900;
      color: var(--accent-green);
    }
    
    /* FAQ */
    .faq-section {
      padding: 7rem 0;
      background: var(--deep-black);
      color: white;
    }
    
    .faq-section .section-title {
      color: white;
    }
    
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    
    .faq-item {
      border-bottom: 1px solid rgba(255,255,255,0.2);
    }
    
    .faq-question {
      width: 100%;
      padding: 24px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      font-size: 1.2rem;
      color: white;
      background: transparent;
      border: none;
      text-align: left;
      cursor: pointer;
    }
    
    .faq-question i {
      transition: transform 0.3s ease;
      color: var(--accent-green);
    }
    
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: #CCCCCC;
      line-height: 1.7;
    }
    
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 20px;
    }
    
    .faq-item.active .faq-question i {
      transform: rotate(180deg);
    }
    
    /* Final CTA */
    .final-cta {
      padding: 6rem 0;
      background: var(--primary-red);
      text-align: center;
      color: white;
    }
    
    .final-cta h2 {
      font-size: 2.8rem;
    }
    
    /* Footer */
    .main-footer {
      background: var(--deep-black);
      color: #CCC;
      padding: 4rem 0 2rem;
    }
    
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 40px;
    }
    
    .footer-brand p {
      margin-top: 1rem;
    }
    
    .footer-links a {
      display: block;
      margin-bottom: 10px;
      color: #AAA;
    }
    
    .footer-links a:hover {
      color: var(--accent-green);
    }
    
    .badge-group i {
      font-size: 2rem;
      margin-right: 15px;
      color: var(--accent-green);
    }
    
    @media (max-width: 1024px) {
      .advantages-grid { grid-template-columns: repeat(2,1fr); }
      .features-layout { flex-direction: column; }
      .feature-tabs { flex-direction: row; flex-wrap: wrap; }
    }
    
    @media (max-width: 768px) {
      .hamburger { display: block; }
      .nav-menu {
        position: fixed; top: 72px; left: 0; width: 100%; height: 0;
        background: white; flex-direction: column; overflow: hidden;
        transition: height 0.3s ease; gap: 0;
      }
      .nav-menu.open { height: calc(100vh - 72px); padding: 40px 0; }
      .hero-grid { grid-template-columns: 1fr; }
      .advantages-grid { grid-template-columns: 1fr; }
      .usecase-grid { grid-template-columns: 1fr; }
      .stats-grid { grid-template-columns: 1fr 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
    }