/* ===== 重置基础样式 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
    border: 0;
}

body {
    font-family: 'Segoe UI', Roboto, sans-serif;
    color: #333;
    line-height: 1.6;
    background-color: #1a2f3f;
    transition: background-color 0.3s, color 0.3s;
}

/* ===== 浅色模式 ===== */
body.light-mode {
    background-color: #f5f5f5;
    color: #222;
}

body.light-mode .top-bar {
    background: rgba(0, 0, 0, 0.2);
}

body.light-mode .download-card,
body.light-mode .footer-info-card {
    background: rgba(40, 40, 40, 0.9);
    border-color: rgba(255,255,255,0.3);
}

body.light-mode .download-item {
    background: rgba(0,0,0,0.05);
    border-color: #ccc;
}

body.light-mode .download-item:hover {
    background: rgba(0,0,0,0.1);
}

body.light-mode .download-info p {
    color: #666;
}

/* ===== 第一屏：背景图区域，flex 布局 ===== */
.hero {
    position: relative;
    width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
}

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: -1;
}

.top-bar {
    background: rgba(0, 0, 0, 0.35);
    height: 10vh;
    width: 100%;
    padding: 0 5%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    color: white;
    backdrop-filter: blur(2px);
    z-index: 1;
}

.logo .logo-img {
    width: 80px;
    height: 80px;
    border-radius: 20px;
    object-fit: cover;
    box-shadow: 0 4px 10px rgba(0,0,0,0.3);
    display: block;
}

.contact a {
    color: white;
    text-decoration: none;
    margin-left: 2rem;
    font-size: 1.2rem;
    transition: opacity 0.2s;
}

.contact a:hover {
    opacity: 0.8;
}

.contact i {
    margin-right: 0.5rem;
}

.hero-content {
    text-align: center;
    color: white;
    text-shadow: 2px 2px 5px black;
    margin: 2rem 0 1rem;
    z-index: 1;
}

.hero-content h1 {
    font-size: 4rem;
    margin-bottom: 1rem;
}

.hero-content p {
    font-size: 1.5rem;
}

/* 下载卡片容器，flex 居中，并容纳卡片和底部信息框 */
.download-card-wrapper {
    flex: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    z-index: 1;
    gap: 1.5rem;
}

/* 下载卡片样式 */
.download-card {
    background: rgba(30, 30, 40, 0.85);
    backdrop-filter: blur(8px);
    border-radius: 30px;
    padding: 2rem;
    border: 1px solid rgba(255,255,255,0.2);
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    width: 100%;
    max-width: 800px;
}

.download-card h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: #ffaa33;
    font-size: 2rem;
}

.download-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.download-item {
    background: rgba(255,255,255,0.1);
    border-radius: 20px;
    padding: 1.2rem 2rem;
    transition: all 0.3s ease;
    border: 1px solid rgba(255,255,255,0.2);
}

.download-item:hover {
    transform: translateY(-3px);
    background: rgba(255,255,255,0.2);
    border-color: rgba(255,255,255,0.5);
}

.download-link {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    text-decoration: none;
    color: white;
}

.download-link i {
    font-size: 2.5rem;
    width: 50px;
    text-align: center;
    color: #ffaa33;
}

.download-info {
    flex: 1;
}

.download-info h3 {
    font-size: 1.4rem;
    margin-bottom: 0.3rem;
}

.download-info p {
    font-size: 0.9rem;
    color: #ccc;
}

.download-badge {
    background: #3498db;
    padding: 0.3rem 1rem;
    border-radius: 30px;
    font-size: 0.8rem;
    font-weight: bold;
}

/* 备案信息浅黑色框 */
.footer-info-card {
    background: rgba(30, 30, 40, 0.7);
    backdrop-filter: blur(8px);
    border-radius: 20px;
    padding: 1rem 2rem;
    border: 1px solid rgba(255,255,255,0.2);
    text-align: center;
    width: 100%;
    max-width: 800px;
    color: #ddd;
    font-size: 0.9rem;
}

.footer-info-card a {
    color: #ffaa33;
    text-decoration: none;
    transition: opacity 0.2s;
}

.footer-info-card a:hover {
    opacity: 0.8;
    text-decoration: underline;
}

/* ===== 模式切换按钮 ===== */
.theme-switcher {
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 2000;
}

.theme-btn {
    width: 48px;
    height: 48px;
    border-radius: 12px;
    background: rgba(0,0,0,0.6);
    border: 2px solid rgba(255,255,255,0.5);
    color: white;
    font-size: 1.6rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    backdrop-filter: blur(4px);
    transition: all 0.2s;
}

.theme-btn:hover {
    background: rgba(0,0,0,0.8);
    border-color: white;
}

.theme-menu {
    position: absolute;
    bottom: 58px;
    right: 0;
    background: rgba(30,30,30,0.9);
    backdrop-filter: blur(8px);
    border-radius: 8px;
    padding: 8px 0;
    display: none;
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    border: 1px solid rgba(255,255,255,0.2);
}

.theme-option {
    padding: 8px 16px;
    color: white;
    cursor: pointer;
    white-space: nowrap;
    font-size: 0.9rem;
    transition: background 0.2s;
}

.theme-option:hover {
    background: rgba(255,255,255,0.2);
}

body.light-mode .theme-btn {
    background: rgba(255,255,255,0.7);
    color: #333;
    border-color: #666;
}

body.light-mode .theme-menu {
    background: rgba(240,240,240,0.95);
    border-color: #ccc;
}

body.light-mode .theme-option {
    color: #333;
}

body.light-mode .theme-option:hover {
    background: rgba(0,0,0,0.1);
}

/* ===== 响应式 ===== */
@media (max-width: 768px) {
    .top-bar {
        height: 10vh;
        padding: 0 1rem;
    }
    .logo .logo-img {
        width: 60px;
        height: 60px;
    }
    .contact a {
        margin-left: 1rem;
        font-size: 1rem;
    }
    .hero-content h1 {
        font-size: 2.8rem;
    }
    .hero-content p {
        font-size: 1.3rem;
    }
    .download-card-wrapper {
        padding: 1rem;
    }
    .download-card {
        padding: 1.5rem;
    }
    .download-link {
        flex-direction: column;
        text-align: center;
        gap: 0.8rem;
    }
    .download-item {
        text-align: center;
    }
    .download-badge {
        align-self: center;
    }
    .footer-info-card {
        padding: 0.8rem 1rem;
    }
    .theme-btn {
        width: 42px;
        height: 42px;
        font-size: 1.4rem;
    }
    .theme-menu {
        bottom: 52px;
    }
}