/* General Styles */
* {
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #fff;
    color: #333;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: auto;
    overflow: hidden;
    padding: 0 20px;
}

/* --- Sticky Navigation Bar --- */
.sticky-nav-wrapper {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: #E1F2FA; /* 保持截图中的粉色背景 */
    z-index: 1000;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    transition: background-color 0.3s ease; /* 新增：平滑过渡效果 */
}
/* .sticky-nav-wrapper .container 的 padding: 0 20px; 会保持内容居中 */

/* 新增：导航栏滚动后的样式 */
.sticky-nav-wrapper.scrolled-nav {
    background-color: rgba(55, 218, 221, 0.85); /* 半透明粉色，可调整透明度 (0.85) */
}

.header-top-bar-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0; /* 导航栏的垂直内边距 */
}

.logo a {
    font-size: 24px;
    font-weight: bold;
    color: #333;
    text-decoration: none;
    text-transform: uppercase;
}

.main-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
}

.main-nav li {
    margin-left: 25px;
}

.main-nav a {
    text-decoration: none;
    color: #333;
    font-weight: 500;
    font-size: 16px;
}

.main-nav a:hover {
    color: #007bff;
}

/* --- Hero Area --- */
.site-hero-area {
    background-color: #FADADD; /* 粉色背景，现在只用于英雄图片区域 */
    
    /* padding-top 将由 JS 设置，以避免被固定导航栏遮挡 */
}

.hero-image-placeholder {
    background-color: #FEC5D6; /* 英雄图占位符的备用背景色 */
    display: flex;
    align-items:  flex-start;
    justify-content: center;
    color: #864659; /* 英雄图上文字颜色 */
    font-size: 2em;
    font-weight: bold;
    text-align: center;
    background-image: url('placeholder-hero.jpg'); /* 替换为您的英雄图片URL */
    background-size: cover;
    background-position: center;
}

.hero-image-placeholder .hero-text {
    background-color: rgba(250, 218, 221, 0.6); /* 文字背景，增加可读性 */
    padding: 10px 20px;
    border-radius: 5px;
}

.hero-img {
    width: 100%;
    height: 750px;
    object-fit: cover;        /* 保持铺满 */
    object-position: top;     /* ✅ 强制优先显示顶部内容，底部裁剪 */
    display: block;
    border-radius: 8px;
}

/* --- Main Content Area --- */
.main-content-area { /* 用于包裹博客主要内容，方便整体控制 */
    /* 如果需要，可以在这里添加额外的上边距，但目前由 .site-hero-area 的 padding-top 控制 */
}

.blog-main-title {
    text-align: center;
    font-size: 28px;
    color: #333;
    margin: 40px 0 20px 0;
    font-weight: 600;
}

.filter-buttons {
    text-align: center;
    margin-bottom: 30px;
}

.filter-button {
    background-color: #007bff;
    color: white;
    border: none;
    padding: 10px 20px;
    margin: 0 5px;
    border-radius: 5px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 500;
}

.filter-button:hover {
    background-color: #0056b3;
}

.posts-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr); /* 每行两个等宽 */
    gap: 40px;
}

.post-card {
    max-width: 100%;
    width: 100%;
}

/* --- Post Card Styles (Corrected and Improved) --- */
.post-card {
    background: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.post-card-image {
    position: relative;
    overflow: hidden;
}

.post-card-img {
    width: 100%;
    height: auto;
    display: block;
}

.post-card-image .play-icon {
    background-color: rgba(0, 0, 0, 0.5);
    border-radius: 50%;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transition: background-color 0.2s ease-in-out;
    font-size: 0; /* 隐藏原始的 "►" 字符 */
    border: none; /* 确保没有额外的边框 */
}

.post-card-image .play-icon::before {
    content: "";
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 10px 0 10px 15px; /* TopHeight RightWidth BottomHeight LeftWidth */
    border-color: transparent transparent transparent rgba(255, 255, 255, 0.95); /* 三角形颜色 */
    display: block;
    margin-left: 3px; /* 根据实际效果微调此值以使三角形视觉居中 */
}

.post-card-image .play-icon:hover {
    background-color: rgba(0, 0, 0, 0.7); /* 悬停时背景变暗 */
}

.post-card-image .image-title-overlay {
    position: absolute;
    top: 15px;
    left: 50%;
    transform: translateX(-50%);
    color: white;
    background-color: rgba(0,0,0,0.6);
    padding: 5px 15px;
    border-radius: 3px;
    font-size: 1em;
    font-weight: bold;
    text-align: center;
    white-space: nowrap;
}

.post-card-image .image-subtitle-overlay {
    position: absolute;
    top: 48px; /* 示例值，请根据 image-title-overlay 的实际高度和间距调整 */
    left: 50%;
    transform: translateX(-50%);
    color: #eee;
    background-color: rgba(0,0,0,0.5);
    padding: 2px 8px;
    border-radius: 3px;
    font-size: 0.8em;
    white-space: nowrap;
}

.polytopia-watermark {
    position: absolute;
    bottom: 10px;
    left: 10px;
    color: rgba(255, 255, 255, 0.6);
    background-color: rgba(0,0,0,0.4);
    padding: 2px 5px;
    border-radius: 2px;
    font-size: 0.7em;
    text-transform: uppercase;
}

.post-card-content {
    padding: 20px;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.post-card-content h2 {
    margin-top: 0;
    margin-bottom: 5px;
    font-size: 1.3em;
    color: #222;
    font-weight: 600;
}

.post-card-content .date {
    font-size: 0.85em;
    color: #666;
    margin-bottom: 15px;
    display: block;
}

.post-card-content p {
    font-size: 0.95em;
    color: #444;
    margin-bottom: 15px;
    flex-grow: 1;
}

.post-card-content .go-there-link {
    color: #007bff;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95em;
    align-self: flex-start;
}

.post-card-content .go-there-link:hover {
    text-decoration: underline;
}

/* --- Footer Styles --- */
footer {
    background: #222;
    color: #ccc;
    text-align: center;
    padding: 40px 20px 20px 20px;
    margin-top: 40px;
}

.footer-top-social {
    margin-bottom: 30px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.footer-top-social a {
    color: #fff;
    text-decoration: none;
    font-size: 1.3em;
    margin: 0 12px;
}

.footer-top-social a:hover {
    color: #00A2FF;
}

footer .footer-columns {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    margin-bottom: 30px;
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

footer .footer-column {
    flex: 1;
    min-width: 200px;
    margin: 10px 20px;
    text-align: left;
}

footer .footer-column h4 {
    color: #fff;
    border-bottom: none;
    padding-bottom: 5px;
    margin-bottom: 15px;
    font-size: 1.1em;
    font-weight: 600;
}

footer .footer-column ul {
    list-style: none;
    padding: 0;
}

footer .footer-column ul li {
    margin-bottom: 10px;
}

footer .footer-column ul li a {
    color: #bbb;
    font-size: 0.95em;
}

footer .footer-column ul li a:hover {
    color: #fff;
}

.community-channels-title {
    font-size: 1.4em;
    color: #fff;
    margin-top: 40px;
    margin-bottom: 20px;
    font-weight: 600;
}

.footer-bottom-social {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    margin-bottom: 30px;
}

.footer-bottom-social a {
    background-color: #333;
    color: #fff;
    text-decoration: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.2em;
    margin: 20px 20px;
    transition: background-color 0.3s ease;
}

.footer-bottom-social a:hover {
    background-color: #007bff;
}

footer .copyright {
    font-size: 0.9em;
    color: #888;
    margin-top: 20px;
}

.blog-main-subtitle {
    text-align: center;
    font-size: 18px;
    color: #555;
    margin-top: 0;
    margin-bottom: 30px;
}


/* --- Responsive Adjustments --- */
@media (max-width: 768px) {
    .header-top-bar-content { /* 调整固定导航栏在小屏幕上的表现 */
        flex-direction: column;
        padding: 10px 0; /* 减少垂直内边距 */
    }
    .logo {
        margin-bottom: 10px;
    }
    .main-nav ul {
        justify-content: center;
        flex-wrap: wrap;
    }
    .main-nav li {
        margin: 5px 10px;
    }
.posts-grid {
    grid-template-columns: 1fr;
}
    .site-hero-area {
        /* padding-top will be dynamically adjusted by JS */
        padding-top: 0 !important;
        margin-top: 0;
    }

    
    
    .hero-image-placeholder {
        height: 200px; /* 减小英雄图高度 */
        font-size: 1.5em;
    }
    .blog-main-title {
        font-size: 24px;
    }
    .filter-button {
        padding: 8px 15px;
        font-size: 14px;
    }
    .posts-grid {
        grid-template-columns: 1fr; /* 单列博文 */
    }
    .container { /* 全局 container 调整 */
        width: 95%;
        padding: 0 10px;
    }
    /* 固定导航栏内的 .container 也继承此处的 padding */

    footer .footer-columns {
        flex-direction: column;
        align-items: center;
    }
    footer .footer-column {
        text-align: center;
        margin-bottom: 25px;
        width: 100%;
    }
    footer .footer-column h4 {
         text-align: center;
    }
    .footer-top-social {
        margin-bottom: 20px;
    }
    .community-channels-title {
        margin-top: 20px;
        font-size: 1.2em;
    }
    .footer-bottom-social a {
        width: 36px;
        height: 36px;
        font-size: 1.1em;
        margin: 5px;
    }
}

