/* ============================================================
   纸飞机 官网 - 独立样式表
   文件: css/style.css
   说明: 包含全局变量、布局、组件及响应式
   ============================================================ */

/* ---------- 全局变量 ---------- */
body { font-family: "Microsoft YaHei", sans-serif; margin: 0; padding: 0; background: #fff; color: #333; line-height: 1.6; }
        .container { max-width: 1140px; margin: 0 auto; padding: 0 15px; }
        
        /* 强制所有链接文字颜色为 #0088CC */
        a { text-decoration: none; transition: 0.3s; color: #0088cc; }
        a:hover { color: #005588; }

        /* 统一标题颜色为 #0088CC */
        h1, h2, h3, h4 { color: #0088cc; }

        /* 导航栏 */
        .header { background: #fff; padding: 15px 0; border-bottom: 1px solid #f2f2f2; position: sticky; top: 0; z-index: 1000; }
        .nav-content { display: flex; align-items: center; justify-content: space-between; }
        .logo-box { display: flex; align-items: center; }
        .logo-box img { height: 40px; max-width: 220px; object-fit: contain; }
        .nav-links a { color: #0088cc; margin-left: 25px; font-size: 16px; font-weight: 500; }

        /* 下载主视觉区 */
        .hero-section { background: #fff; padding: 60px 0 80px; text-align: center; }
        .hero-section h1 { font-size: 42px; margin-bottom: 15px; }
        .hero-section p { font-size: 18px; color: #777; margin-bottom: 50px; max-width: 750px; margin-left: auto; margin-right: auto; }

        .download-triangle { display: flex; flex-direction: column; align-items: center; gap: 50px; }
        .download-row { display: flex; justify-content: center; gap: 40px; flex-wrap: wrap; }
        .download-unit { display: flex; flex-direction: column; align-items: center; width: 320px; }
        .demo-screen { width: 100%; height: 180px; object-fit: contain; margin-bottom: 20px; filter: drop-shadow(0 5px 15px rgba(0,0,0,0.08)); }

        .btn-blue { display: inline-flex; align-items: center; justify-content: center; background: #0088cc; color: #fff !important; width: 220px; padding: 12px 0; border-radius: 8px; font-size: 17px; font-weight: bold; box-shadow: 0 4px 12px rgba(0,136,204,0.15); }
        .btn-blue:hover { background: #0077bb; transform: translateY(-2px); }
        .btn-blue img { width: 22px; height: 22px; margin-right: 10px; }

        /* 功能板块 */
        .features-grid { padding: 60px 0; border-top: 1px solid #f5f5f5; }
        .grid-container { display: grid; grid-template-columns: repeat(4, 1fr); gap: 30px; }
        .grid-item { text-align: center; }
        .grid-item img { width: 60px; height: 60px; margin-bottom: 15px; }
        .grid-item h4 { font-size: 18px; margin-bottom: 10px; }
        .grid-item p { font-size: 14px; color: #888; }
        
        /* 双栏介绍区 */
        .info-section { padding: 70px 0; background: #fff; border-top: 1px solid #eee; }
        .info-grid { display: flex; gap: 60px; }
        .info-column { flex: 1; }
        .info-column h2 { font-size: 28px; border-left: 5px solid #0088cc; padding-left: 15px; margin-bottom: 35px; }
        
        .item-box { display: flex; margin-bottom: 25px; }
        .item-icon { width: 35px; height: 35px; background: #e1f3ff; color: #0088cc; border-radius: 50%; display: flex; align-items: center; justify-content: center; margin-right: 15px; flex-shrink: 0; font-weight: bold; }
        .item-text h4 { margin: 0 0 5px 0; font-size: 17px; }
        .item-text p { margin: 0; color: #777; font-size: 14px; }
        
        /* FAQ 样式 */
        .faq-box { background: #fff; padding: 20px; border-radius: 10px; margin-bottom: 15px; border: 1px solid #eee; }
        .faq-box h4 { margin: 0 0 10px 0; }
        .faq-box p { margin: 0; color: #777; font-size: 14px; }

        .footer { padding: 50px 0; text-align: center; color: #999; font-size: 14px; border-top: 1px solid #eee; }

        @media (max-width: 992px) {
            .grid-container { grid-template-columns: repeat(2, 1fr); }
            .info-grid { flex-direction: column; }
        }