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

body {
    font-family: "Microsoft YaHei", "Segoe UI", Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

header {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    color: white;
    padding: 25px 20px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

header h1 {
    font-size: 2.2em;
    margin-bottom: 8px;
    background: linear-gradient(90deg, #00d9ff, #00ff88);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

header p {
    font-size: 1.1em;
    color: #a0a0a0;
}

.container {
    flex: 1;
    display: flex;
    max-width: 1400px;
    margin: 30px auto;
    width: 95%;
    gap: 25px;
    padding: 0 15px;
}

.sidebar {
    width: 280px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    max-height: calc(100vh - 180px);
}

.sidebar-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 18px 20px;
    font-size: 1.2em;
    font-weight: bold;
}

.sidebar-menu {
    flex: 1;
    overflow-y: auto;
    padding: 10px 0;
}

.menu-item {
    padding: 14px 20px;
    cursor: pointer;
    border-left: 4px solid transparent;
    transition: all 0.3s ease;
    font-size: 0.95em;
    color: #333;
}

.menu-item:hover {
    background: #f0f4ff;
    border-left-color: #667eea;
    padding-left: 25px;
}

.menu-item.active {
    background: linear-gradient(90deg, #f0f4ff 0%, #e8ecff 100%);
    border-left-color: #667eea;
    color: #667eea;
    font-weight: bold;
}

.content-area {
    flex: 1;
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
    padding: 35px 40px;
    max-height: calc(100vh - 180px);
    overflow-y: auto;
}

.content-area h2 {
    color: #1a1a2e;
    font-size: 1.8em;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 3px solid #667eea;
}

.content-area .article-meta {
    color: #888;
    font-size: 0.9em;
    margin-bottom: 25px;
    padding-bottom: 15px;
    border-bottom: 1px solid #eee;
}

.content-area .article-content {
    line-height: 1.9;
    color: #444;
    font-size: 1.05em;
}

.content-area .article-content p {
    margin-bottom: 18px;
}

.content-area .article-content h3 {
    color: #333;
    font-size: 1.3em;
    margin: 25px 0 15px 0;
}

.content-area .article-content ul,
.content-area .article-content ol {
    margin: 15px 0;
    padding-left: 30px;
}

.content-area .article-content li {
    margin-bottom: 10px;
}

.content-area .article-content strong {
    color: #667eea;
}

.content-area .article-content .highlight {
    background: linear-gradient(90deg, #f0f4ff 0%, #e8ecff 100%);
    padding: 15px 20px;
    border-left: 4px solid #667eea;
    margin: 20px 0;
    border-radius: 0 8px 8px 0;
}

.welcome-content {
    text-align: center;
    padding: 60px 20px;
}

.welcome-content h2 {
    color: #667eea;
    margin-bottom: 20px;
}

.welcome-content p {
    color: #666;
    font-size: 1.1em;
    line-height: 1.8;
}

footer {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    color: #888;
    text-align: center;
    padding: 20px;
    font-size: 0.9em;
    margin-top: auto;
}

footer a {
    color: #00d9ff;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        max-height: 300px;
    }

    .content-area {
        max-height: none;
    }
}