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

   /* 全局重置 & 基础 */
   * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            background-color: #ffffff;
            color: #1e1e1e;
            line-height: 1.6;
            -webkit-font-smoothing: antialiased;
        }

        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 24px;
        }

        :root {
            --telegram-blue: #0088cc;
            --telegram-blue-hover: #006699;
        }

        /* ===== 导航栏 ===== */
        .navbar {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 20px 0;
            border-bottom: 1px solid rgba(0, 136, 204, 0.08);
            flex-wrap: wrap;
            gap: 16px;
        }

        .nav-logo img {
            height: 44px;
            width: auto;
            display: block;
        }

        .nav-links {
            display: flex;
            align-items: center;
            gap: 36px;
            list-style: none;
            flex-wrap: wrap;
        }

        .nav-links a {
            font-size: 16px;
            font-weight: 500;
            color: var(--telegram-blue);
            text-decoration: none;
            transition: color 0.2s, border-bottom 0.2s;
            padding-bottom: 4px;
            border-bottom: 2px solid transparent;
        }

        .nav-links a:hover {
            color: var(--telegram-blue-hover);
            border-bottom-color: var(--telegram-blue);
        }

        /* ===== 下载中心 Hero ===== */
        .download-hero {
            text-align: center;
            padding: 60px 0 40px 0;
        }

        .download-hero h1 {
            font-size: 42px;
            font-weight: 700;
            letter-spacing: -0.5px;
            margin-bottom: 12px;
        }

        .download-hero h1 i {
            color: var(--telegram-blue);
            margin-right: 10px;
        }

        .download-hero p {
            font-size: 18px;
            color: #3a3a3a;
            max-width: 560px;
            margin: 0 auto 16px;
        }

        /* ===== 平台下载卡片 (两行, 每行3个) ===== */
        .download-grid {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 28px;
            padding: 20px 0 48px 0;
        }

        @media (max-width: 820px) {
            .download-grid {
                grid-template-columns: repeat(2, 1fr);
            }
        }

        @media (max-width: 540px) {
            .download-grid {
                grid-template-columns: 1fr;
            }
        }

        .download-card {
            background: #f8fafc;
            border-radius: 28px;
            padding: 32px 20px 28px;
            text-align: center;
            border: 1px solid #edf2f6;
            transition: box-shadow 0.25s, transform 0.2s;
        }

        .download-card:hover {
            box-shadow: 0 12px 32px rgba(0, 136, 204, 0.08);
            transform: translateY(-4px);
        }

        .download-card .icon {
            font-size: 48px;
            color: var(--telegram-blue);
            margin-bottom: 16px;
            display: inline-block;
        }

        .download-card h3 {
            font-size: 22px;
            font-weight: 600;
            margin-bottom: 6px;
        }

        .download-card .version-tag {
            display: inline-block;
            background: var(--telegram-blue);
            color: #fff;
            font-size: 12px;
            padding: 2px 16px;
            border-radius: 30px;
            margin-bottom: 12px;
            font-weight: 500;
        }

        .download-card .meta {
            font-size: 14px;
            color: #5d6b7a;
            margin-bottom: 18px;
        }

        /* ===== 按钮样式 ===== */
        .download-btn {
            background-color: var(--telegram-blue);
            color: #fff;
            border: none;
            padding: 12px 28px;
            border-radius: 40px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: background 0.2s, transform 0.1s;
            box-shadow: 0 4px 12px rgba(0, 136, 204, 0.2);
            display: inline-flex;
            align-items: center;
            gap: 10px;
            text-decoration: none;
            font-family: inherit;
        }

        .download-btn i {
            font-size: 18px;
        }

        .download-btn:hover {
            background-color: var(--telegram-blue-hover);
            transform: scale(1.02);
        }

        .download-btn:active {
            transform: scale(0.97);
        }

        .download-btn:disabled {
            cursor: not-allowed;
            opacity: 0.7 !important;
            transform: none !important;
        }

        /* ===== 附加信息 (版本说明 / 汉化) ===== */
        .extra-section {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 40px;
            padding: 40px 0 48px 0;
            border-top: 1px solid #f0f0f0;
        }

        @media (max-width: 700px) {
            .extra-section {
                grid-template-columns: 1fr;
                gap: 32px;
            }
        }

        .extra-block h3 {
            font-size: 22px;
            font-weight: 600;
            margin-bottom: 20px;
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .extra-block h3 i {
            color: var(--telegram-blue);
        }

        .extra-block ul {
            list-style: none;
        }

        .extra-block ul li {
            padding: 10px 0 10px 32px;
            position: relative;
            border-bottom: 1px solid #f2f2f2;
            font-size: 16px;
        }

        .extra-block ul li::before {
            content: "✓";
            color: var(--telegram-blue);
            font-weight: 700;
            position: absolute;
            left: 0;
            top: 10px;
        }

        .extra-block ul li:last-child {
            border-bottom: none;
        }

        /* ===== 常见问题 (8个, 一行2个) ===== */
        .faq-section {
            padding: 40px 0 40px 0;
            border-top: 1px solid #f0f0f0;
        }

        .faq-section .section-title {
            font-size: 28px;
            font-weight: 700;
            text-align: center;
            margin-bottom: 20px;
        }

        .faq-section .section-title i {
            color: var(--telegram-blue);
            margin-right: 8px;
        }

        .faq-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 20px 32px;
            margin-top: 8px;
        }

        @media (max-width: 700px) {
            .faq-grid {
                grid-template-columns: 1fr;
            }
        }

        .faq-item {
            background: #f9fbfd;
            border-radius: 20px;
            padding: 18px 22px;
            border: 1px solid #edf2f7;
            transition: background 0.15s;
        }

        .faq-item:hover {
            background: #f2f7fc;
        }

        .faq-item h4 {
            font-size: 17px;
            font-weight: 600;
            display: flex;
            align-items: flex-start;
            gap: 10px;
            margin-bottom: 4px;
        }

        .faq-item h4 i {
            color: var(--telegram-blue);
            font-size: 18px;
            margin-top: 2px;
        }

        .faq-item p {
            font-size: 15px;
            color: #3d4a5a;
            margin-left: 32px;
        }

        /* ===== 页脚 ===== */
        .footer {
            border-top: 1px solid #eaeef2;
            padding: 40px 0 32px 0;
            margin-top: 20px;
            background: #fafcfe;
        }

        .footer-content {
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            align-items: center;
            gap: 20px;
        }

        .footer-copy {
            font-size: 14px;
            color: #5d6b7a;
        }

        .footer-social a {
            color: var(--telegram-blue);
            margin-left: 20px;
            font-size: 20px;
            transition: color 0.2s;
            text-decoration: none;
        }

        .footer-social a:hover {
            color: var(--telegram-blue-hover);
        }

        .footer-links a {
            color: #3d4a5a;
            text-decoration: none;
            margin: 0 12px;
            font-size: 14px;
        }

        .footer-links a:hover {
            color: var(--telegram-blue);
        }