:root {
            --primary-color: #2563eb;
            --primary-hover: #1d4ed8;
            --secondary-color: #4b5563;
            --secondary-hover: #374151;
            --text-color: #1f2937;
            --bg-color: #ffffff;
            --section-bg: #f9fafb;
            --border-color: #e5e7eb;
        }
        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            color: var(--text-color);
            line-height: 1.7;
            background-color: var(--bg-color);
        }
        header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 1rem 5%;
            border-bottom: 1px solid var(--border-color);
            position: sticky;
            top: 0;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(5px);
            z-index: 1000;
        }
        .logo {
            display: flex;
            align-items: center;
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
            text-decoration: none;
        }
        .logo img {
            width: auto;
            height: 36px;
            margin-right: 12px;
            display: block;
        }
        .nav-container {
            display: flex;
            align-items: center;
        }
        nav a {
            margin-left: 1.5rem;
            text-decoration: none;
            color: var(--text-color);
            font-size: 0.95rem;
            transition: color 0.2s;
        }
        nav a:hover {
            color: var(--primary-color);
        }
        .github-repo-btn {
            display: inline-flex;
            align-items: center;
            background-color: #111827;
            color: #ffffff;
            padding: 0.5rem 1rem;
            border-radius: 6px;
            font-size: 0.9rem;
            text-decoration: none;
            margin-left: 2rem;
            transition: background-color 0.2s;
            font-weight: 500;
        }
        .github-repo-btn:hover {
            background-color: #1f2937;
        }
        .github-repo-btn svg {
            width: 18px;
            height: 18px;
            margin-right: 8px;
            fill: currentColor;
        }
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 2rem 5%;
        }
        .hero-section {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 2rem;
            align-items: center;
            padding: 4rem 0;
        }
        .hero-text h1 {
            font-size: 2.5rem;
            line-height: 1.2;
            margin-bottom: 1.5rem;
        }
        .hero-text p {
            font-size: 1.1rem;
            color: #4b5563;
            margin-bottom: 2rem;
        }
        .banner-placeholder {
            width: 100%;
            height: 350px;
            background-color: #f3f4f6;
            border: 2px dashed #d1d5db;
            border-radius: 8px;
            display: flex;
            align-items: center;
            justify-content: center;
            position: relative;
            overflow: hidden;
        }
        .banner-placeholder img {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            object-fit: cover;
            opacity: 1;
        }
        .banner-placeholder::after {
            content: "首页主 Banner 预留多媒体图片位 [1200x700]";
            color: #9ca3af;
            font-size: 0.95rem;
            text-align: center;
            padding: 20px;
        }
        .grid-4 {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
            gap: 1.5rem;
            margin-top: 2rem;
        }
        .download-card {
            background: #ffffff;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 2rem 1.5rem;
            text-align: center;
            box-shadow: 0 1px 3px rgba(0,0,0,0.05);
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }
        .download-card h3 {
            font-size: 1.4rem;
            margin-bottom: 0.5rem;
            color: #111827;
        }
        .download-card .version-info {
            font-size: 0.85rem;
            color: #6b7280;
            margin-bottom: 1.5rem;
        }
        .btn-group {
            display: flex;
            flex-direction: column;
            gap: 0.75rem;
        }
        .btn-main {
            display: block;
            background-color: var(--primary-color);
            color: #ffffff;
            padding: 0.75rem 1rem;
            border-radius: 6px;
            text-decoration: none;
            font-weight: 500;
            font-size: 0.95rem;
            transition: background-color 0.2s;
        }
        .btn-main:hover {
            background-color: var(--primary-hover);
        }
        .btn-sub {
            display: block;
            background-color: var(--section-bg);
            color: var(--secondary-color);
            padding: 0.65rem 1rem;
            border-radius: 6px;
            text-decoration: none;
            font-size: 0.85rem;
            font-weight: 500;
            border: 1px solid var(--border-color);
            transition: all 0.2s;
        }
        .btn-sub:hover {
            background-color: #e5e7eb;
            color: var(--secondary-hover);
        }
        .grid-3 {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 2rem;
            margin-top: 2rem;
        }
        .card {
            background: #ffffff;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 2rem;
            box-shadow: 0 1px 3px rgba(0,0,0,0.05);
        }
        .card h3 {
            margin-bottom: 1rem;
            font-size: 1.3rem;
            color: #111827;
        }
        .card ul {
            list-style-type: none;
        }
        .card ul li {
            margin-bottom: 0.75rem;
            position: relative;
            padding-left: 1.2rem;
        }
        .card ul li::before {
            content: "•";
            color: var(--primary-color);
            font-weight: bold;
            position: absolute;
            left: 0;
        }
        .card ul li a {
            color: var(--primary-color);
            text-decoration: none;
        }
        .card ul li a:hover {
            text-decoration: underline;
        }
        section {
            padding: 4rem 0;
        }
        section:nth-of-type(even) {
            background-color: var(--section-bg);
            border-top: 1px solid var(--border-color);
            border-bottom: 1px solid var(--border-color);
        }
        h2 {
            font-size: 2rem;
            margin-bottom: 1.5rem;
            text-align: center;
        }
        .section-desc {
            text-align: center;
            max-width: 800px;
            margin: -1rem auto 3rem auto;
            color: #4b5563;
        }
        .concept-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 2.5rem;
        }
        .concept-item h3 {
            font-size: 1.25rem;
            margin-bottom: 0.5rem;
            color: #111827;
        }
        .concept-item p {
            color: #4b5563;
            font-size: 0.95rem;
        }
        footer {
            background: #111827;
            color: #ffffff;
            padding: 3rem 5%;
            text-align: center;
            font-size: 0.9rem;
        }
        @media (max-width: 912px) {
            header {
                flex-direction: column;
                gap: 1rem;
                padding: 1.5rem 5%;
            }
            .nav-container {
                flex-direction: column;
                gap: 1rem;
                width: 100%;
            }
            nav {
                display: flex;
                justify-content: center;
                flex-wrap: wrap;
                gap: 0.5rem;
            }
            nav a {
                margin-left: 0.75rem;
                margin-right: 0.75rem;
            }
            .github-repo-btn {
                margin-left: 0;
            }
            .hero-section {
                grid-template-columns: 1fr;
                text-align: center;
            }
            .concept-grid {
                grid-template-columns: 1fr;
                gap: 1.5rem;
            }
        }