/* 全局设置 */
body, html { 
    margin: 0; 
    padding: 0; 
    font-family: 'Georgia', serif; 
    height: 100%; 
    /* 桌面端保持无滚动，移动端在下面 @media 里开启滚动 */
    overflow: hidden; 
}

/* --- 背景设置 --- */
.hero-bg {
    background-color: #2c3e50; 
    background-image: url('../assets/yunnan.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    
    height: 100vh;
    width: 100vw;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    position: relative;
}

/* 遮罩层 */
.overlay {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0, 0, 0, 0.5); 
    z-index: 1; 
    pointer-events: none;
}

/* --- 标题框 --- */
.title-box {
    position: relative;
    z-index: 2;
    background: rgba(255, 255, 255, 0.08);
    backdrop-filter: blur(10px);
    padding: 40px 70px;
    border: 1px solid rgba(255, 255, 255, 0.25);
    text-align: center;
    color: white;
    margin-bottom: 50px; /* 稍微减小与卡片的距离 */
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.3);
    border-radius: 4px;
    transition: transform 0.3s;
}

.title-box h1 { 
    margin: 0; 
    font-size: 3.8rem; 
    letter-spacing: 3px; 
    text-transform: uppercase; 
    text-shadow: 0 2px 10px rgba(0,0,0,0.5);
}

.title-box p { 
    margin-top: 12px; 
    font-size: 1.3rem; 
    font-style: italic; 
    opacity: 0.95; 
    letter-spacing: 1px;
}

/* --- 导航卡片容器 --- */
.card-container {
    position: relative;
    z-index: 2;
    display: flex;
    gap: 20px; /* 减小卡片之间的间距 */
    flex-direction: row; 
}

/* --- ★★★ 核心修改：卡片样式 ★★★ --- */
.nav-card {
    background: rgba(20, 20, 20, 0.75);
    backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: white;
    
    /* 修改点 1：减小宽度，让整体更精致 */
    width: 220px; 
    
    /* 修改点 2：大幅减小内边距，让卡片变“扁” */
    padding: 20px 15px; 
    
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: flex;
    flex-direction: column;
    align-items: center;
    border-radius: 6px;
}

.nav-card:hover {
    background: rgba(255, 255, 255, 0.95);
    color: #1a1a1a;
    transform: translateY(-5px); /* 悬浮幅度也改小一点 */
}

.nav-card h3 { 
    /* 修改点 3：减小标题下方的间距 */
    margin: 0 0 5px 0; 
    
    font-family: sans-serif; 
    text-transform: uppercase; 
    letter-spacing: 1px; 
    font-size: 0.8rem; /* 字体稍微调小 */
    color: #f1c40f;
    transition: color 0.3s;
}

.nav-card:hover h3 { 
    color: #d35400; 
}

.nav-card h2 { 
    margin: 0; 
    font-size: 1.3rem; /* 字体稍微调小 */
    line-height: 1.2; 
    font-weight: 500;
}

.nav-card .arrow { 
    /* 修改点 4：大幅减小箭头的上方间距，防止卡片被撑高 */
    margin-top: 10px; 
    font-size: 1.2rem; 
}

/* ========================================= */
/* --- 移动端适配 (Mobile Responsive) --- */
/* ========================================= */

@media screen and (max-width: 768px) {
    
    /* 允许页面滚动 */
    body, html {
        height: auto;
        overflow-y: auto; 
    }

    .hero-bg {
        height: auto;
        min-height: 100vh;
        padding: 40px 20px;
        box-sizing: border-box; 
        justify-content: flex-start; 
    }

    /* 手机端标题调整 */
    .title-box {
        padding: 25px 15px;
        margin-top: 30px;
        margin-bottom: 30px;
        width: 85%;
    }

    .title-box h1 {
        font-size: 2rem; 
    }

    .title-box p {
        font-size: 0.9rem; 
    }

    /* 手机端卡片排列 */
    .card-container {
        flex-direction: column; 
        width: 100%;
        align-items: center; 
        padding-bottom: 40px;
        gap: 15px; /* 手机上卡片靠得紧一点 */
    }

    /* --- ★★★ 手机端卡片特化：更宽、更扁 ★★★ --- */
    .nav-card {
        /* 宽度变大，看起来像一个横条按钮 */
        width: 90%; 
        max-width: 350px; 
        
        /* 进一步减小上下内边距 */
        padding: 15px 20px; 
        
        /* 可选：如果你想让手机上文字横向排列（左边字右边箭头），可以解开下面这行注释 */
        /* flex-direction: row; justify-content: space-between; align-items: center; */
    }
    
    /* 手机上箭头稍微小一点 */
    .nav-card .arrow {
        margin-top: 8px; /* 极小的间距 */
        font-size: 1.1rem;
    }
}