:root {
    --bg-color: #f0f2f5;
    --text-color: #333;
    --container-bg: #fff;
    --border-color: #ddd;
    --button-bg: #007bff;
    --button-text: #fff;
    --article-bg: #f8f9fa;
}

body.dark-mode {
    --bg-color: #18191a;
    --text-color: #e4e6eb;
    --container-bg: #242526;
    --border-color: #3a3b3c;
    --button-bg: #0056b3;
    --article-bg: #2d2e2f;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 20px;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: 1200px; /* 扩大整体UI界面 */
    margin: 0 auto;
    background-color: var(--container-bg);
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 15px;
}

@media (min-width: 768px) {
    header {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }
}

.header-actions {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

#admin-password {
    padding: 8px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background-color: var(--bg-color);
    color: var(--text-color);
}

.search-box input {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 20px;
    background-color: var(--bg-color);
    color: var(--text-color);
    width: 200px;
    transition: width 0.3s;
}

.search-box input:focus {
    width: 300px;
    outline: none;
    border-color: var(--button-bg);
}

.highlight {
    background-color: #ffeb3b;
    color: #000;
    font-weight: bold;
    padding: 0 2px;
    border-radius: 2px;
}

/* 独立滚动条设置 */
.article-list, .post-list {
    max-height: 600px;
    overflow-y: auto;
    padding-right: 10px;
}

/* 自定义滚动条样式 */
.article-list::-webkit-scrollbar, .post-list::-webkit-scrollbar {
    width: 6px;
}

.article-list::-webkit-scrollbar-thumb, .post-list::-webkit-scrollbar-thumb {
    background-color: var(--border-color);
    border-radius: 10px;
}

.article-list::-webkit-scrollbar-track, .post-list::-webkit-scrollbar-track {
    background: transparent;
}

.channel-btn, #theme-toggle, #admin-login, .publish-tab, #submit-post, #submit-article, .admin-btn {
    padding: 10px 15px;
    border-radius: 8px;
    border: none;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.2s;
}

.channel-btn {
    flex: 1;
    background: none;
    color: var(--text-color);
    border-bottom: 3px solid transparent;
}

.channel-btn.active {
    border-bottom-color: var(--button-bg);
    font-weight: bold;
}

nav {
    display: flex;
    border-bottom: 1px solid var(--border-color);
}

main {
    padding: 30px;
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.channel-content {
    display: none;
}

.channel-content.active {
    display: grid;
    grid-template-columns: 1fr;
    gap: 30px;
}

@media (min-width: 992px) {
    .channel-content.active {
        grid-template-columns: 1fr 1fr; /* 校园墙和文章区域并排 */
    }
}

/* 文章列表样式 */
.article-item {
    background-color: var(--article-bg);
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 10px;
    cursor: pointer;
    border: 1px solid var(--border-color);
    transition: transform 0.2s;
}

.article-item:hover {
    transform: translateX(5px);
}

.article-item h4 {
    margin: 0;
    color: var(--button-bg);
}

/* 帖子样式 */
.post {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 15px;
}

.post.pinned {
    border: 2px solid #ffc107;
    background-color: rgba(255, 193, 7, 0.05);
}

.post img {
    max-width: 100%;
    border-radius: 8px;
    margin-top: 10px;
}

/* 发布区域样式 */
footer {
    padding: 30px;
    border-top: 1px solid var(--border-color);
    background-color: var(--article-bg);
}

.publish-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.publish-tab {
    background: var(--container-bg);
    color: var(--text-color);
}

.publish-tab.active {
    background: var(--button-bg);
    color: #white;
}

.post-form {
    display: none;
}

.post-form.active {
    display: block;
}

.post-form input, .post-form textarea {
    width: 100%;
    padding: 12px;
    margin-bottom: 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--container-bg);
    color: var(--text-color);
    box-sizing: border-box;
}

/* 弹窗样式 */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
}

.modal-content {
    background-color: var(--container-bg);
    margin: 5% auto;
    padding: 40px;
    border-radius: 15px;
    width: 80%;
    max-width: 800px;
    max-height: 80vh;
    overflow-y: auto;
    position: relative;
}

.close-modal {
    position: absolute;
    right: 20px;
    top: 15px;
    font-size: 28px;
    cursor: pointer;
}

.admin-only {
    display: none;
}

body.admin-mode .admin-only {
    display: inline-flex;
    gap: 5px;
    margin-top: 10px;
}

.pin-badge {
    display: none;
    background: #ffc107;
    color: #000;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: bold;
    margin-bottom: 10px;
}

.post.pinned .pin-badge {
    display: inline-block;
}