/* =========================================
   全局变量与基础重置
   ========================================= */
:root {
    /* 将主要颜色提炼为变量，方便日后一键修改全局色调 */
    --bg-light-blue: #bfe2f4;
    --bg-dark-blue: #85c7e9;
    --text-main: #333333;
    --text-muted: #666666;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg-light-blue); 
    font-family: "Microsoft YaHei", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    -webkit-font-smoothing: antialiased;
}

/* =========================================
   无障碍访问 (a11y)
   ========================================= */
/* 为使用键盘 Tab 键导航的用户提供清晰的焦点反馈 */
a:focus-visible {
    outline: 3px dashed #FF5500;
    outline-offset: 4px;
    border-radius: 4px;
}

/* =========================================
   Header 顶部大图区域
   ========================================= */
.header {
    width: 100%;
    max-width: 1920px;
    height: 650px;
    margin: 0 auto;
    background: url('../img/1.png') no-repeat center top;
    background-size: cover;
    position: relative; 
}

.header-logo {
    display: block;
    position: absolute;
    left: max(20px, calc(50% - 600px + 20px)); 
    top: 40px;
    width: 309px;
    height: 77px;
    transition: transform 0.2s ease;
}

.header-logo img {
    width: 100%;
    height: 100%;
    display: block;
}

/* =========================================
   Main 主体内容区域
   ========================================= */
.main-content {
    width: 100%;
    display: flex;
    justify-content: center;
}

.content-wrapper {
    width: 90%;
    max-width: 1350px; 
    background-color: #ffffff; 
    padding: 50px 0 80px 0;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.05); 
}

/* 胶带背景区域 (PC端) */
.tape-section {
    width: 90%;
    max-width: 1189px; 
    margin: 0 auto 50px auto;
    aspect-ratio: 1189 / 342;
    background: url('../img/2.png') no-repeat center center;
    background-size: contain; 
    display: flex;
    align-items: center;
    justify-content: center;
}

.tape-text {
    width: 80%; 
    font-size: 18px;
    line-height: 2;
    color: var(--text-main);
    padding: 20px;
}

.tape-text p {
    text-indent: 2em; 
    text-align: justify; 
}

/* 视频图片 Grid 布局区 */
.video-grid {
    width: 90%;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px; 
}

.video-grid a {
    display: block;
    width: 100%;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.video-grid img {
    width: 100%;
    height: auto; 
    display: block;
    border-radius: 8px; 
}

/* =========================================
   仅在支持鼠标的设备上启用悬浮动效
   避免移动端点击时卡在 hover 状态
   ========================================= */
@media (hover: hover) {
    .header-logo:hover {
        transform: scale(1.02); 
    }
    
    .video-grid a:hover {
        transform: translateY(-5px); 
        box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1); 
    }
}

/* =========================================
   Footer 页尾区域
   ========================================= */
.footer {
    width: 100%;
    min-height: 172px; 
    background-color: var(--bg-dark-blue); 
    margin: 0 auto;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 16px; 
    color: var(--text-main); 
    padding: 20px 0;
}

.footer a {
    color: var(--text-main);
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

.footer-inner {
    display: flex;
    align-items: center;
    gap: 30px;
}

.footer-text-area {
    display: flex;
    flex-direction: column;
    align-items: center;
    line-height: 2;
}

.footer-links {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
}

.footer-item {
    display: flex;
    align-items: center;
}

.footer-icon {
    width: 18px;
    height: 20px;
    margin-right: 5px;
    vertical-align: middle;
}

.separator {
    margin: 0 15px;
    color: var(--text-muted);
}

.footer-badge img {
    max-width: 50px;
    display: block;
}

/* =========================================
   移动端响应式 (Media Queries)
   ========================================= */
@media only screen and (max-width: 768px) {
    .header {
        height: 200px; 
        background: url('../img/1.jpg') no-repeat center center; 
        background-size: cover;
    }
    
    .header-logo {
        width: 160px; 
        height: auto;
        left: 20px; 
        top: 20px;  
    }

    .content-wrapper {
        width: 100%; 
        padding: 30px 15px 50px 15px;
    }

    /* 移动端改为 CSS 卡片式便签设计，防止图片拉伸 */
    .tape-section {
        aspect-ratio: auto; 
        background-image: none; 
        background-color: #f4f9fc; 
        border-radius: 6px; 
        border-left: 5px solid var(--bg-dark-blue); 
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04); 
        padding: 20px; 
        margin-bottom: 30px;
    }

    .tape-text {
        width: 100%; 
        font-size: 15px; 
        line-height: 1.8;
        padding: 0; 
    }

    /* 网格适配：1行1个 */
    .video-grid {
        width: 100%;
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .footer {
        height: auto;
        padding: 30px 0; 
        font-size: 14px;
        background-color: var(--bg-dark-blue); 
    }

    .footer-inner {
        flex-direction: column; 
        gap: 20px;
    }

    .footer-links {
        flex-direction: column; 
        gap: 10px; 
    }

    .separator {
        display: none; 
    }

    .footer-text-area {
        gap: 10px; 
    }
}