:root {
    --bg-color: #0a0a0a;
    --text-primary: #ffffff;
    --text-secondary: #a0a0a0;
    --border-color: #363636;
    --accent-color: #009688;
    --accent-color-hover: #00bcd4;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--bg-color);
    color: var(--text-primary);
    overflow-x: hidden;
    position: relative;
}

#tsparticles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

.page-wrapper {
    position: relative;
    z-index: 1;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
}

.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 0;
    border-bottom: 1px solid var(--border-color);
    position: relative;
    z-index: 9999;
}

.logo {
    text-align: left;
}

.logo-text-main {
    font-size: 28px;
    font-weight: 700;
    letter-spacing: 2px;
    background: linear-gradient(90deg, #ffffff 60%, #009688 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo-text-sub {
    font-size: 12px;
    font-weight: 500;
    color: var(--text-secondary);
    letter-spacing: 1px;
    display: block;
    margin-top: -4px;
}

.logo-image {
    max-height: 40px;
}

.main-nav {
    display: flex;
    gap: 40px;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 16px;
    font-weight: 500;
    transition: color 0.2s ease;
}

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

.btn {
    padding: 10px 24px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    transition: background-color 0.2s ease;
}

.btn-primary {
    background-color: #111;
    color: var(--text-primary);
    border: 1px solid #333;
    border-radius: 8px;
    transition: all 0.2s ease;
}

.btn-primary:hover {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 150, 136, 0.3);
}

.hero-section {
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    min-height: calc(100vh - 90px); /* 90px is approx header height */
}

.hero-title {
    font-size: 72px;
    font-weight: 700;
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: 24px;
    color: var(--text-secondary);
}

.main-footer {
    padding: 20px;
    text-align: center;
    position: relative;
    z-index: 1;
}

.main-footer a {
    color: var(--text-secondary);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 14px;
}

.main-footer a:hover {
    color: var(--text-primary);
}

.beian-icon {
    width: 16px;
    height: 16px;
}

.main-content {
    display: grid;
    grid-template-columns: 200px 1fr 350px;
    gap: 40px;
    align-items: center;
    padding: 60px 0;
    min-height: calc(100vh - 180px); /* Adjust based on header/footer height */
}

.side-nav {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.side-nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 18px;
    font-weight: 500;
    transition: color 0.2s ease;
}

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

.right-sidebar {
    display: flex;
    justify-content: flex-end;
}

.announcements {
    width: 100%;
}

.announcement-item {
    display: flex;
    align-items: center;
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 14px;
    cursor: pointer;
    transition: background-color 0.2s;
}

.announcement-item:hover {
    background-color: rgba(255, 255, 255, 0.05);
}

.tag {
    padding: 4px 8px;
    border-radius: 4px;
    font-weight: 600;
    margin-right: 12px;
}

.featured-tag {
    background-color: #e6a23c;
    color: #fff;
}

.announcement-tag {
    background-color: var(--accent-color);
    color: var(--text-primary);
}

.announcement-text {
    color: var(--text-secondary);
    flex-grow: 1;
}

.announcement-title {
    color: var(--text-primary);
    flex-grow: 1;
    font-weight: 600;
}

.announcement-date {
    color: var(--text-secondary);
}

.view-more {
    display: block;
    text-align: right;
    margin-top: 16px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 14px;
}

.view-more:hover {
    color: var(--text-primary);
}

/* 课程列表样式 */
.course-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top: 3px solid var(--accent-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 16px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-text {
    font-size: 16px;
    color: var(--text-secondary);
}

.course-item {
    background: linear-gradient(135deg, #1a1a1a 0%, #2a2a2a 100%);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 20px;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.course-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-color), var(--accent-color-hover));
}

.course-item:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(0, 150, 136, 0.15);
    border-color: var(--accent-color);
}

.course-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
}

.course-image {
    width: 80px;
    height: 60px;
    object-fit: cover;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.course-info {
    flex: 1;
}

.course-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
    line-height: 1.4;
}

.course-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.course-access-type {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.course-access-type.member {
    background: linear-gradient(135deg, #ff6b35, #f7931e);
    color: white;
}

.course-access-type.purchased {
    background: linear-gradient(135deg, var(--accent-color), var(--accent-color-hover));
    color: white;
}

.course-price {
    color: #ff6b35;
    font-weight: 600;
}

.course-progress {
    margin-bottom: 16px;
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: var(--border-color);
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: 8px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), var(--accent-color-hover));
    border-radius: 3px;
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 14px;
    color: var(--text-secondary);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.course-actions {
    display: flex;
    gap: 12px;
}

.course-btn {
    flex: 1;
    padding: 10px 16px;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.course-btn.primary {
    background: linear-gradient(135deg, var(--accent-color), var(--accent-color-hover));
    color: white;
}

.course-btn.primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 150, 136, 0.3);
}

.course-btn.secondary {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}

.course-btn.secondary:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    text-align: center;
}

.empty-icon {
    font-size: 48px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.empty-text {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.empty-subtext {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .course-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }
    
    .course-image {
        width: 100%;
        height: 120px;
    }
    
    .course-actions {
        flex-direction: column;
    }
    
    .course-meta {
        flex-wrap: wrap;
        gap: 8px;
    }
}

/* 统一后台侧边栏二级菜单缩进和样式 */
.sidebar-menu .submenu {
    padding-left: 24px;
    background: none;
}
.sidebar-menu .submenu a {
    display: block;
    padding: 8px 16px;
    color: #ccc;
    font-size: 14px;
    background: none;
    border-radius: 6px;
    margin: 2px 0;
    transition: background 0.2s, color 0.2s;
}
.sidebar-menu .submenu a.active,
.sidebar-menu .submenu a:hover {
    color: #fff;
    background: #2d8cf0;
}