/* 论坛基础样式表 */

:root {
    --primary-color: #3b82f6;
    --secondary-color: #6b7280;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --info-color: #06b6d4;
    --light-bg: #f9fafb;
    --dark-bg: #1f2937;
    --border-color: #e5e7eb;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --card-bg: #ffffff;
    --sidebar-bg: #f3f4f6;
    --header-bg: #ffffff;
    --hover-bg: #f3f4f6;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background-color: var(--light-bg);
    color: var(--text-primary);
    line-height: 1.6;
}

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

/* --- Header Styles --- */
header {
    background: var(--header-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: color 0.2s;
}

.nav-link:hover, .nav-link.active {
    color: var(--primary-color);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--primary-color);
}

.user-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

/* --- Buttons --- */
.btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    text-decoration: none;
    display: inline-block;
    transition: all 0.2s;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: #2563eb;
}

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: white;
}

/* --- Layout --- */
.main-layout {
    display: flex;
    gap: 2rem;
    margin-top: 2rem;
}

/* --- Sidebar Styles --- */
.sidebar {
    flex: 0 0 250px;
    background: var(--card-bg);
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    height: fit-content;
}

.sidebar-section {
    margin-bottom: 1.5rem;
}

.sidebar-title {
    font-size: 0.85rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    letter-spacing: 0.5px;
}

.sidebar-nav {
    list-style: none;
}

.sidebar-item {
    margin-bottom: 0.5rem;
}

.sidebar-link {
    display: flex;
    align-items: center;
    padding: 0.5rem;
    text-decoration: none;
    color: var(--text-primary);
    border-radius: 4px;
    transition: all 0.2s;
}

.sidebar-link:hover, .sidebar-link.active {
    background-color: var(--hover-bg);
    color: var(--primary-color);
}

.sidebar-link i {
    margin-right: 0.75rem;
    width: 20px;
    text-align: center;
}

/* --- Main Content --- */
.main-content {
    flex: 1;
}

.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.page-title {
    font-size: 1.5rem;
    color: var(--text-primary);
}

/* --- Card Styles --- */
.card {
    background: var(--card-bg);
    border-radius: 8px;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    margin-bottom: 1.5rem;
    overflow: hidden;
}

.card-header {
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    font-weight: 600;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.card-body {
    padding: 1.5rem;
}

/* --- Topic List --- */
.topic-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.topic-item {
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    transition: all 0.2s;
    cursor: pointer;
}

.topic-item:hover {
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transform: translateY(-1px);
}

.topic-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.topic-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.5rem;
}

.topic-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin: 0;
    flex: 1;
}

.topic-title a {
    text-decoration: none;
    color: var(--text-primary);
}

.topic-title a:hover {
    color: var(--primary-color);
}

.topic-meta {
    display: flex;
    gap: 1rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.topic-category {
    background-color: #e0f2fe;
    color: var(--info-color);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
}

.topic-stats {
    display: flex;
    gap: 1rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* --- Category Grid --- */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
}

.category-card {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    transition: all 0.2s;
}

.category-card:hover {
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.category-name {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.category-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.category-stats {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* --- Footer --- */
footer {
    background: var(--header-bg);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    margin-top: 3rem;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* --- Loading Spinner --- */
.spinner {
    border: 4px solid rgba(0, 0, 0, 0.1);
    border-left-color: var(--primary-color);
    border-radius: 50%;
    width: 24px;
    height: 24px;
    animation: spin 1s linear infinite;
    display: inline-block;
    vertical-align: middle;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* --- Modal Styles --- */
.modal {
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    display: flex;
    justify-content: center;
    align-items: center;
}

.modal-content {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    width: 90%;
    max-width: 500px;
}

.close {
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

.close:hover {
    color: var(--danger-color);
}

.form-group {
    margin-bottom: 1rem;
}

.form-control {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .main-layout {
        flex-direction: column;
    }
    
    .sidebar {
        flex: none;
    }
    
    .nav-menu {
        display: none;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
}