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

body {
    font-family: 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #f8fafc;
    min-height: 100vh;
    display: flex;
    color: #334155;
}

/* 左侧导航栏 */
.sidebar {
    width: 260px;
    background: #ffffff;
    height: 100vh;
    position: fixed;
    overflow-y: auto;
    border-right: 1px solid #e2e8f0;
    z-index: 1000;
    box-shadow: 2px 0 10px rgba(0, 0, 0, 0.05);
}

.sidebar-header {
    padding: 2rem 1.5rem;
    text-align: center;
    background: #ffffff;
    border-bottom: 1px solid #e2e8f0;
    margin-bottom: 1rem;
}

.sidebar-header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 0.8rem;
    letter-spacing: 1px;
}

.sidebar-header p {
    font-size: 0.9rem;
    color: #64748b;
    letter-spacing: 0.5px;
}

.nav-menu {
    padding: 0 1rem;
}

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

.nav-title {
    padding: 0.8rem 1rem;
    color: #475569;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    border-radius: 8px;
    text-align: center;
    letter-spacing: 0.5px;
}

.nav-title:hover {
    background: #f1f5f9;
    color: #0f172a;
    transform: translateY(-1px);
}

.nav-title.active {
    background: #f1f5f9;
    color: #0f172a;
    font-weight: 600;
}

/* 移除箭头符号相关样式 */
.nav-title::after {
    display: none;
}

.submenu {
    display: none;
    padding: 0.4rem 0;
    margin-left: 0.5rem;
}

.submenu.active {
    display: block;
    animation: slideDown 0.2s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-5px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.submenu a {
    display: block;
    padding: 0.7rem 1rem;
    color: #64748b;
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    border-radius: 8px;
    margin: 0.2rem 0;
    text-align: center;
    letter-spacing: 0.3px;
}

.submenu a:hover {
    background: #f1f5f9;
    color: #0f172a;
    transform: translateY(-1px);
}

/* 右侧内容区 */
.main-content {
    flex: 1;
    margin-left: 260px;
    padding: 2rem;
    min-height: 100vh;
    background: #f8fafc;
}

.content-frame {
    width: 100%;
    height: calc(100vh - 4rem);
    border: none;
    border-radius: 12px;
    background: #ffffff;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
}

/* 欢迎页面样式 */
.welcome-content {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

/* 背景视频 */
.background-video {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 1;
}

.video-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
    z-index: 2;
}

.welcome-title {
    font-size: 2.5rem;
    font-weight: 600;
    color: #ffffff;
    margin-bottom: 1rem;
    letter-spacing: 2px;
    position: relative;
    z-index: 3;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.welcome-subtitle {
    font-size: 1.2rem;
    color: #e2e8f0;
    margin-bottom: 2rem;
    letter-spacing: 1px;
    position: relative;
    z-index: 3;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.welcome-features {
    display: flex;
    gap: 2rem;
    margin-top: 2rem;
    position: relative;
    z-index: 3;
}

.feature-item {
    background: rgba(255, 255, 255, 0.1);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.feature-item:hover {
    transform: translateY(-10px);
    background: rgba(255, 255, 255, 0.2);
    box-shadow: 0 20px 30px rgba(0, 0, 0, 0.3);
}

.feature-title {
    font-size: 1.2rem;
    color: #ffffff;
    margin-bottom: 0.5rem;
    position: relative;
    display: inline-block;
}

.feature-desc {
    color: #e2e8f0;
    font-size: 0.9rem;
    transform: translateY(0);
    transition: transform 0.3s ease;
}

/* 动画关键帧 */
@keyframes titleFloat {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

@keyframes subtitleFade {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.7;
    }
}

/* 滚动条美化 */
::-webkit-scrollbar {
    width: 4px;
}

::-webkit-scrollbar-track {
    background: #f1f5f9;
}

::-webkit-scrollbar-thumb {
    background: #cbd5e1;
    border-radius: 2px;
}

::-webkit-scrollbar-thumb:hover {
    background: #94a3b8;
}

/* 粒子背景 */
.particles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}

.particle {
    position: absolute;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 50%;
    pointer-events: none;
    animation: particleFloat 15s linear infinite;
}

@keyframes particleFloat {
    0% {
        transform: translateY(0) rotate(0deg);
    }
    100% {
        transform: translateY(-100vh) rotate(360deg);
    }
}

.welcome-title, .welcome-subtitle, .welcome-features {
    position: relative;
    z-index: 2;
}