:root {
            --bg-color: #ffffff;
            --sidebar-bg: #ffffff;
            --card-bg: #E2F2FF;
            --text-main: #0f0f0f;
            --text-secondary: #aaaaaa;
            --accent-color: #3ea6ff;
            --accent-hover: #65b8ff;
            --danger-color: #ff4d4d;
            --success-color: #2ba640;
            --border-color: #3f3f3f;
            --header-height: 60px;
            --sidebar-width: 210px;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            outline: none;
        }

        body {
            font-family: 'Microsoft YaHei', Helvetica, Arial, sans-serif;
            background-color: var(--bg-color);
            color: var(--text-main);
            font-size: 14px;
            overflow: hidden; /* 防止主滚动条，内容区域独立滚动 */
            height: 100vh;
            display: flex;
            flex-direction: column;
        }

        a {
            color: var(--text-main);
            text-decoration: none;
        }

        a:hover {
            color: var(--text-main);
            text-decoration: none;
        }

        /* --- 滚动条样式 --- */
        ::-webkit-scrollbar {
            width: 8px;
        }
        ::-webkit-scrollbar-track {
            background: transparent;
        }
        ::-webkit-scrollbar-thumb {
            background: #555;
            border-radius: 4px;
        }
        ::-webkit-scrollbar-thumb:hover {
            background: #777;
        }

        /* --- 通用组件 --- */
        .btn {
            padding: 8px 16px;
            border-radius: 4px;
            border: none;
            cursor: pointer;
            font-size: 14px;
            font-weight: 500;
            transition: all 0.2s;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 6px;
        }
        .btn-primary {
            background-color: var(--accent-color);
            color: #fff;
        }
        .btn-primary:hover {
            background-color: var(--accent-hover);
        }
        .btn-secondary {
            background-color: #fff;
            color: #000;
        }
        .btn-secondary:hover {
            background-color: #fff;
        }
        .btn-danger {
            background-color: var(--danger-color);
            color: white;
        }
        .btn-icon {
            padding: 8px;
            border-radius: 20px;
            background: transparent;
            color: var(--text-secondary);
        }
        .btn-icon:hover {
            background-color: #000;
        }

        .fa {
            width: 16px;
            height: 16px;
            background-color: #fff;
            vertical-align: middle;
        }

        .avatar {
            width: 32px;
            height: 32px;
            border-radius: 20px;
            background-color: #fff;
            object-fit: cover;
            vertical-align: middle;
        }

        .input-group {
            margin-bottom: 15px;
        }
        .input-group label {
            display: block;
            margin-bottom: 6px;
            color: var(--text-secondary);
            font-size: 14px;
        }
        .form-control {
            width: 100%;
            padding: 10px 12px;
            background-color: #fff;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            color: var(--text-main);
            font-size: 14px;
        }
        .form-control:focus {
            border-color: var(--accent-color);
        }

        /* --- 顶部导航栏 --- */
        .header {
            height: var(--header-height);
            background-color: var(--bg-color);
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0 20px;
            border-bottom: 1px solid var(--border-color);
            z-index: 100;
        }

        .header-left {
            display: flex;
            align-items: center;
            gap: 4px;
        }

        .logo {
            display: flex;
            align-items: center;
            letter-spacing: -0.5px;
        }
        .logo img { height: 40px;vertical-align: middle; }

        .search-bar {
            display: flex;
            flex: 1;
            max-width: 600px;
            margin-left: 20px;
        }
        .search-input {
            flex: 1;
            padding: 8px 12px;
            background-color: #ffffff;
            border: 1px solid var(--border-color);
            border-right: none;
            border-radius: 20px 0 0 20px;
            color: var(--text-main);
        }
        .search-btn {
            padding: 0 20px;
            background-color: #ffffff;
            border: 1px solid var(--border-color);
            border-radius: 0 20px 20px 0;
            color: var(--text-secondary);
            cursor: pointer;
        }
        .search-btn:hover { color: #000000; }

        .header-right {
            display: flex;
            align-items: center;
            gap: 15px;
        }
        .user-item {
            display: flex;
            align-items: center;
            gap: 6px;
            padding: 0;
            color: var(--text-main);
            text-decoration: none;
            font-size: 14px;
            cursor: pointer;
            transition: background 0.2s;
        }
        .user-item:hover {
            color: var(--accent-color);
        }

        /* --- 侧边栏 --- */
        .sidebar {
            width: var(--sidebar-width);
            background-color: var(--sidebar-bg);
            height: calc(100vh - var(--header-height));
            overflow-y: auto;
            padding: 10px 0;
            position: fixed;
            left: 0;
            top: var(--header-height);
            transition: transform 0.3s ease;
            z-index: 90;
        }

        .nav-group {
            padding: 10px 0;
            border-bottom: 1px solid rgba(255,255,255,0.05);
        }
        .nav-group:last-child { border-bottom: none; }
        .nav-title {
            padding: 0 24px;
            margin-bottom: 8px;
            font-size: 12px;
            font-weight: bold;
            color: var(--text-secondary);
            text-transform: uppercase;
        }

        .nav-item {
            display: flex;
            align-items: center;
            gap: 6px;
            padding: 10px 24px;
            color: var(--text-main);
            text-decoration: none;
            font-size: 14px;
            cursor: pointer;
            transition: background 0.2s;
        }
        .nav-item:hover {
            font-weight: bold;
            color: var(--accent-color);
        }
        .nav-item2 {
            display: flex;
            align-items: center;
            gap: 6px;
            padding: 10px 24px;
            color: var(--text-main);
            text-decoration: none;
            font-size: 14px;
            cursor: pointer;
            transition: background 0.2s;
            font-weight: bold;
            color: var(--accent-color);
        }
        .nav-item2:hover {
            font-weight: bold;
            color: var(--accent-color);
        }

        /* --- 主内容区域 --- */
        .main-content {
            margin-left: var(--sidebar-width);
            flex: 1;
            height: calc(100vh - var(--header-height));
            overflow-y: auto;
            padding: 20px 20px 0;
            background-color: var(--bg-color);
            transition: margin-left 0.3s ease;
        }

        /* --- 页面部分通用样式 --- */
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .section-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 20px;
        }
        .section-title {
            font-size: 24px;
            font-weight: bold;
        }

        /* 页脚 */
        .footer {
            background-color: var(--bg-color);
            padding: 10px 20px;
            margin-top: 30px;
            text-align: center;
            border-top: 1px solid var(--border-color);
        }

        .copyright {
            color: var(--text-main);
            text-align: center;
            gap: 10px;
            margin: 10px 0;
        }

        .copyright a {
            color: var(--text-main);
            text-decoration: none;
        }

        .copyright a:hover {
            color: var(--text-main);
            text-decoration: none;
        }

        .copyright img {
            margin: 0 5px;
            width: 20px;
            height: 20px;
            vertical-align: middle;
        }

        /* --- 控制面板 --- */
        .main-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
        .main-section { background: var(--card-bg); padding: 25px; border-radius: 8px; }

        /* --- 首页 --- */
        .category-tabs {
            display: flex;
            gap: 10px;
            margin-bottom: 20px;
            padding-bottom: 5px;
        }
        .cat-chip {
            padding: 6px 8px;
            background-color: rgba(255,255,255,0.1);
            font-size: 14px;
            border-radius: 8px;
            white-space: nowrap;
            cursor: pointer;
            transition: all 0.2s;
        }
        .cat-chip.active, .cat-chip:hover {
            background-color: var(--text-main);
            color: var(--bg-color);
        }

        .video-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 20px;
        }

        /* --- 视频卡片 --- */
        .video-card {
            cursor: pointer;
            transition: transform 0.2s;
        }
        .video-card:hover { transform: scale(1.02); }
        .thumbnail {
            width: 100%;
            height: auto;
            background-color: #333;
            border-radius: 8px;
            position: relative;
            overflow: hidden;
        }
        .thumbnail img { width: 100%; height: 100%; object-fit: cover; vertical-align: middle; }
        .duration {
            position: absolute;
            bottom: 8px;
            right: 8px;
            background-color: rgba(0,0,0,0.8);
            padding: 2px 6px;
            border-radius: 4px;
            color: #ffffff;
            font-size: 12px;
        }
        .video-info { padding-top: 10px; display: flex; gap: 10px; }
        .video-meta h3 { font-size: 14px; line-height: 1.4; margin-bottom: 4px; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
        .video-meta p { font-size: 12px; color: var(--text-secondary); }

        /* --- 播放页面 --- */
        .playback-container {
            display: grid;
            grid-template-columns: 1fr 350px;
            gap: 24px;
        }
        .video-player-wrapper {
            width: 100%;
            background: #000;
            border-radius: 12px;
            overflow: hidden;
            aspect-ratio: 16/9;
            margin-bottom: 16px;
        }
        .video-player {
            width: 100%;
            height: 100%;
        }
        .playback-info h1 { font-size: 20px; margin-bottom: 10px; }
        .playback-stats { display: flex; color: var(--text-secondary); }
        .playback-stats span { display: flex; gap: 5px;}
        .playback-actions { display: flex; gap: 10px; border-bottom: 1px solid var(--border-color); padding: 15px 0; }
        .playback-intro { border-bottom: 1px solid var(--border-color); padding: 15px 0; }
        .playback-next { display: flex;justify-content: space-between;border-bottom: 1px solid var(--border-color); padding: 15px 0; }

        .related-video { display: flex; gap: 10px; margin-bottom: 15px; cursor: pointer; }
        .related-thumb { width: 160px; height: 90px; background: #333; border-radius: 6px; overflow: hidden; flex-shrink: 0; }
        .related-thumb img { width: 100%; height: 100%; object-fit: cover; vertical-align: middle; }
        .related-info h4 { font-size: 14px; margin-bottom: 4px; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
        .related-info p { font-size: 12px; color: var(--text-secondary); }

        /* --- 上传页面 --- */
        .upload-area {
            border: 2px dashed var(--border-color);
            border-radius: 12px;
            padding: 40px;
            text-align: center;
            background-color: rgba(255,255,255,0.02);
            cursor: pointer;
            transition: all 0.2s;
        }
        .upload-area:hover { border-color: var(--accent-color); background-color: rgba(62, 166, 255, 0.05); }
        .upload-icon { font-size: 48px; color: var(--text-secondary); margin-bottom: 15px; }
        .upload-form-container { margin-top: 30px; }
        .progress-bar { height: 4px; background-color: #333; border-radius: 2px; overflow: hidden; margin: 15px 0; display: none; }
        .progress-fill { height: 100%; background-color: var(--accent-color); width: 0%; transition: width 0.3s; }

        /* --- 编辑页面 --- */
        .editor-layout { display: grid; grid-template-columns: 2fr 1fr; gap: 20px; }
        .timeline-editor { background: #1a1a1a; padding: 20px; border-radius: 8px; border: 1px solid var(--border-color); margin-top: 15px; }
        .track { height: 40px; background: #333; margin-bottom: 8px; border-radius: 4px; position: relative; overflow: hidden; }
        .clip { position: absolute; height: 100%; background: var(--accent-color); border-radius: 4px; border: 1px solid #fff; display: flex; align-items: center; justify-content: center; font-size: 10px; overflow: hidden; cursor: move; }
        .playhead { position: absolute; top: 0; bottom: 0; left: 50%; width: 2px; background: var(--danger-color); z-index: 10; }

        /* --- 收藏夹页面 --- */
        .fav-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 20px; margin-bottom: 30px; }
        .fav-card { background-color: var(--card-bg); padding: 20px; border-radius: 8px; }

        /* --- 管理页面 --- */
        .stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin-bottom: 30px; }
        .stat-card { background-color: var(--card-bg); padding: 20px; border-radius: 8px; }
        .stat-label { color: var(--text-secondary); font-size: 14px; }
        .stat-val { color: var(--text-main); font-size: 24px; font-weight: bold; margin-bottom: 5px; }

        .data-table { width: 100%; border-collapse: collapse; background: var(--bg-color); overflow: hidden; }
        .data-table th, .data-table td { padding: 12px 15px; text-align: center; border: 1px solid var(--border-color); }
        .data-table th { background-color: var(--card-bg); color: var(--text-main); font-weight: 500; font-size: 13px; }
        .data-table tr:hover { background-color: var(--card-bg); }
        .status-badge { padding: 4px 8px; border-radius: 4px; font-size: 12px; background: rgba(43, 166, 64, 0.2); color: var(--success-color); }
        .status-badge.review { background: rgba(255, 193, 7, 0.2); color: #ffc107; }

        /* --- 设置页面 --- */
        .settings-container { padding: 25px; }
        .settings-section { background: var(--card-bg); padding: 25px; border-radius: 8px; }
        .settings-header { border-bottom: 1px solid var(--border-color); padding-bottom: 15px; margin-bottom: 20px; }

        /* --- 登录页面 --- */
        .login-container {
            display: flex;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: var(--bg-color);
            align-items: center;
            justify-content: center;
        }
        .login-section { max-width: 300px; background: var(--card-bg); padding: 30px; border-radius: 8px; margin: 20px 0; }
        .login-header { border-bottom: 1px solid var(--border-color); padding-bottom: 15px; margin-bottom: 20px; }
        .login-header h1 { font-size: 30px; margin-bottom: 10px; }

        /* --- 响应式 --- */
        .mobile-menu-btn { display: none; }

        @media (max-width: 1024px) {
            .playback-container { grid-template-columns: 1fr; }
            .sidebar { transform: translateX(-100%); }
            .main-content { margin-left: 0; }
            .sidebar.open { transform: translateX(0); }
            .mobile-menu-btn { display: block; font-size: 20px; cursor: pointer; }
            .stats-grid { grid-template-columns: repeat(2, 1fr); }
            .fav-grid { grid-template-columns: repeat(2, 1fr); }
        }
        @media (max-width: 600px) {
            .logo img { height: 20px; }
            .search-bar { display: none; } /* Mobile hide search for simplicity */
            .stats-grid { grid-template-columns: 1fr; }
            .fav-grid { grid-template-columns: 1fr; }
            .playback-next { display: block; border-bottom: 1px solid var(--border-color); padding: 15px 0; }
            .main-layout { grid-template-columns: 1fr; }
            .main-section img { display: none; }
            .editor-layout { grid-template-columns: 1fr; }
        }