:root {
            --qwen-purple: #615ced;
            --qwen-purple-dark: #4a3fd4;
            --qwen-purple-light: #a7a2f7;
            --qwen-purple-bg: #f0eeff;
            --qwen-violet: #7c5cfc;
            --qwen-violet-dark: #5a3bc4;
            --qwen-white: #ffffff;
            --qwen-gray: #f5f5fa;
            --qwen-text: #1a1a2e;
            --qwen-text-light: #6b6b8a;
            --qwen-accent: #e8e5ff;
            --qwen-gradient: linear-gradient(135deg, #615ced 0%, #7c5cfc 50%, #a78bfa 100%);
            --qwen-gradient-soft: linear-gradient(135deg, #f0eeff 0%, #e8e5ff 100%);
            --qwen-glow: 0 0 30px rgba(97, 92, 237, 0.3);
        }

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

        body {
            font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Helvetica Neue', Arial, sans-serif;
            background: var(--qwen-gray);
            color: var(--qwen-text);
            line-height: 1.6;
        }

        .header {
            background: var(--qwen-gradient);
            color: white;
            padding: 60px 40px 50px;
            text-align: center;
            position: relative;
            overflow: hidden;
        }

        .header::before {
            content: '';
            position: absolute;
            top: -50%; left: -50%;
            width: 200%; height: 200%;
            background: radial-gradient(circle at 30% 70%, rgba(255,255,255,0.1) 0%, transparent 50%),
                        radial-gradient(circle at 70% 30%, rgba(255,255,255,0.08) 0%, transparent 50%);
            animation: float 20s ease-in-out infinite;
        }

        @keyframes float {
            0%, 100% { transform: translate(0, 0) rotate(0deg); }
            33% { transform: translate(2%, -2%) rotate(1deg); }
            66% { transform: translate(-1%, 1%) rotate(-1deg); }
        }

        .header-content { position: relative; z-index: 1; max-width: 900px; margin: 0 auto; }
        .header .tag {
            display: inline-block; background: rgba(255,255,255,0.2); backdrop-filter: blur(10px);
            padding: 6px 18px; border-radius: 20px; font-size: 13px; font-weight: 600;
            letter-spacing: 1.5px; text-transform: uppercase; margin-bottom: 20px;
        }
        .header h1 { font-size: 42px; font-weight: 800; margin-bottom: 12px; letter-spacing: -0.5px; }
        .header .subtitle { font-size: 18px; opacity: 0.9; font-weight: 400; max-width: 600px; margin: 0 auto; }

        .container { max-width: 1300px; margin: 0 auto; padding: 0 24px; }

        /* Navigation tabs */
        .nav-tabs {
            display: flex; gap: 8px; margin: -25px auto 40px; position: relative; z-index: 2;
            max-width: 800px; padding: 0 24px; flex-wrap: wrap; justify-content: center;
        }
        .nav-tab {
            background: white; border: 1px solid rgba(97,92,237,0.1); border-radius: 12px;
            padding: 12px 24px; font-size: 14px; font-weight: 600; color: var(--qwen-text-light);
            cursor: pointer; transition: all 0.2s; box-shadow: 0 2px 12px rgba(0,0,0,0.04);
        }
        .nav-tab:hover { color: var(--qwen-purple); border-color: var(--qwen-purple-light); }
        .nav-tab.active {
            background: var(--qwen-purple); color: white; border-color: var(--qwen-purple);
            box-shadow: 0 4px 20px rgba(97,92,237,0.3);
        }

        /* Sections */
        .section {
            background: white; border-radius: 20px; padding: 40px; margin-bottom: 24px;
            box-shadow: 0 2px 16px rgba(0,0,0,0.04); border: 1px solid rgba(97,92,237,0.06);
            display: none;
        }
        .section.active { display: block; }

        .section-title {
            font-size: 24px; font-weight: 700; color: var(--qwen-purple-dark);
            margin-bottom: 8px; display: flex; align-items: center; gap: 12px;
        }
        .section-title .icon {
            width: 36px; height: 36px; background: var(--qwen-gradient-soft);
            border-radius: 10px; display: flex; align-items: center; justify-content: center;
            font-size: 18px; flex-shrink: 0;
        }
        .section-desc {
            color: var(--qwen-text-light); font-size: 15px; margin-bottom: 28px;
        }

        /* Canvas container */
        .canvas-container {
            background: linear-gradient(135deg, #1a1a2e 0%, #2d2b55 100%);
            border-radius: 16px; padding: 20px; margin: 20px 0;
            box-shadow: inset 0 0 40px rgba(0,0,0,0.3);
            position: relative;
        }
        .canvas-container canvas {
            width: 100%; border-radius: 10px; display: block;
        }
        .canvas-label {
            color: rgba(255,255,255,0.7); font-size: 12px; text-align: center;
            margin-top: 10px; font-style: italic;
        }

        /* Tooltip */
        .tooltip {
            position: absolute; background: white; color: var(--qwen-text);
            border-radius: 10px; padding: 12px 16px; font-size: 13px;
            box-shadow: 0 8px 32px rgba(97,92,237,0.2); border: 1px solid var(--qwen-purple-light);
            pointer-events: none; opacity: 0; transition: opacity 0.2s;
            max-width: 280px; z-index: 100;
        }
        .tooltip.visible { opacity: 1; pointer-events: auto; }
        .tooltip .tt-title { font-weight: 700; color: var(--qwen-purple-dark); margin-bottom: 4px; }
        .tooltip .tt-desc { color: var(--qwen-text-light); line-height: 1.5; }

        /* Info panels */
        .info-panel {
            background: var(--qwen-purple-bg); border-radius: 12px; padding: 20px;
            margin: 16px 0; border-left: 4px solid var(--qwen-purple);
        }
        .info-panel h4 { color: var(--qwen-purple-dark); font-size: 15px; margin-bottom: 6px; }
        .info-panel p { font-size: 14px; color: var(--qwen-text-light); line-height: 1.7; }

        /* Controls */
        .controls {
            display: flex; gap: 12px; margin: 16px 0; flex-wrap: wrap; align-items: center;
        }
        .control-btn {
            background: var(--qwen-gradient); color: white; border: none; border-radius: 10px;
            padding: 10px 20px; font-size: 13px; font-weight: 600; cursor: pointer;
            transition: transform 0.15s, box-shadow 0.15s;
        }
        .control-btn:hover { transform: translateY(-1px); box-shadow: 0 4px 16px rgba(97,92,237,0.3); }
        .control-btn:active { transform: translateY(0); }

        .control-slider {
            display: flex; align-items: center; gap: 10px;
            background: var(--qwen-purple-bg); border-radius: 10px; padding: 8px 16px;
        }
        .control-slider label { font-size: 13px; font-weight: 600; color: var(--qwen-purple-dark); white-space: nowrap; }
        .control-slider input[type="range"] {
            width: 120px; accent-color: var(--qwen-purple);
        }
        .control-slider .val {
            font-size: 13px; font-weight: 700; color: var(--qwen-purple); min-width: 30px; text-align: right;
        }

        /* Step indicator */
        .step-indicator {
            display: flex; align-items: center; justify-content: center; gap: 0;
            margin: 20px 0; flex-wrap: wrap;
        }
        .step {
            display: flex; align-items: center; gap: 8px; padding: 8px 16px;
            font-size: 13px; font-weight: 600; color: var(--qwen-text-light);
            background: var(--qwen-gray); border-radius: 20px; transition: all 0.3s;
        }
        .step.active {
            background: var(--qwen-purple); color: white;
            box-shadow: 0 4px 16px rgba(97,92,237,0.3);
        }
        .step.done { background: var(--qwen-purple-light); color: white; }
        .step-arrow { color: var(--qwen-purple-light); font-size: 18px; margin: 0 4px; }

        /* Grid layout */
        .two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
        @media (max-width: 768px) {
            .header h1 { font-size: 30px; }
            .section { padding: 28px 22px; }
            .two-col { grid-template-columns: 1fr; }
            .nav-tabs { gap: 6px; }
            .nav-tab { padding: 10px 16px; font-size: 13px; }
        }

        /* Expert highlight */
        .expert-grid {
            display: grid; grid-template-columns: repeat(8, 1fr); gap: 8px; margin: 16px 0;
        }
        .expert-cell {
            background: var(--qwen-gray); border: 2px solid transparent; border-radius: 10px;
            padding: 12px 8px; text-align: center; font-size: 12px; font-weight: 600;
            transition: all 0.3s; cursor: default;
        }
        .expert-cell.active {
            background: var(--qwen-purple); color: white; border-color: var(--qwen-purple-dark);
            box-shadow: var(--qwen-glow);
        }
        .expert-cell.shared {
            background: linear-gradient(135deg, #f59e0b, #d97706); color: white;
            border-color: #b45309; box-shadow: 0 0 20px rgba(245,158,11,0.3);
        }
        .expert-cell .expert-num { font-size: 16px; font-weight: 800; }
        .expert-cell .expert-label { font-size: 10px; opacity: 0.8; margin-top: 2px; }

        /* Token visualization */
        .token-row {
            display: flex; gap: 6px; margin: 12px 0; flex-wrap: wrap;
        }
        .token-chip {
            padding: 6px 14px; border-radius: 8px; font-size: 13px; font-weight: 600;
            background: var(--qwen-purple-bg); color: var(--qwen-purple-dark);
            border: 1px solid var(--qwen-purple-light);
        }
        .token-chip.selected {
            background: var(--qwen-purple); color: white; border-color: var(--qwen-purple-dark);
        }

        /* Attention heatmap */
        .heatmap-grid {
            display: grid; gap: 2px; margin: 16px 0;
        }
        .heatmap-cell {
            aspect-ratio: 1; border-radius: 4px; transition: background 0.3s;
            cursor: default;
        }
        .heatmap-cell:hover { transform: scale(1.5); z-index: 10; }

        /* Responsive canvas containers */
        .canvas-container {
            overflow-x: auto;
            -webkit-overflow-scrolling: touch;
        }
        .canvas-container canvas {
            max-width: 100%;
            height: auto;
        }

        .footer {
            text-align: center; padding: 30px; color: var(--qwen-text-light); font-size: 13px;
        }
        .footer a { color: var(--qwen-purple); text-decoration: none; }

        /* Back link */
        .back-link {
            display: inline-flex; align-items: center; gap: 6px;
            color: var(--qwen-purple); font-size: 14px; font-weight: 600;
            text-decoration: none; margin-bottom: 20px; padding: 8px 16px;
            border-radius: 10px; transition: background 0.2s;
        }
        .back-link:hover { background: var(--qwen-purple-bg); }