:root {
            --primary: #3498db;    --success: #27ae60;
            --warning: #f1c40f;    --danger: #e74c3c;
            --text: #2c3e50;       --gray: #95a5a6;
            --border: #e2e8f0;
        }

        body {
            font-family: 'Segoe UI', system-ui, sans-serif;
            max-width: 600px;
            margin: 2rem auto;
            padding: 0 1rem;
            background: #f8fafc;
        }

        .card {
            background: white;
            padding: 2rem;
            border-radius: 12px;
            box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
        }

        .step-indicator {
            display: flex;
            justify-content: space-between;
            margin-bottom: 2rem;
            counter-reset: step;
        }

        .step-item {
            flex: 1;
            text-align: center;
            position: relative;
        }

        .step-item::before {
            counter-increment: step;
            content: counter(step);
            display: block;
            width: 30px;
            height: 30px;
            line-height: 30px;
            border-radius: 50%;
            background: var(--gray);
            color: white;
            margin: 0 auto 0.5rem;
        }

        .step-item.active::before {
            background: var(--primary);
        }

        .step-item.completed::before {
            background: var(--success);
        }

        .step-container {
            display: none;
        }

        .active-step {
            display: block;
        }

        .input-field {
            width: 93%;
            padding: 1rem;
            margin: 1rem 0;
            border: 2px solid var(--border);
            border-radius: 8px;
            font-size: 1.1rem;
        }

        .btn {
            background: var(--primary);
            color: white;
            border: none;
            padding: 1rem 2rem;
            border-radius: 8px;
            cursor: pointer;
            width: 100%;
            font-size: 1.1rem;
            margin-top: 1rem;
            transition: opacity 0.3s;
        }

        .btn:hover {
            opacity: 0.9;
        }

        .warning-box {
            background: #fcf8e3;
            border-left: 4px solid var(--warning);
            padding: 1.5rem;
            margin: 2rem 0;
            border-radius: 6px;
        }

        .version-comparison {
            background: #f8fafc;
            padding: 1.5rem;
            border-radius: 8px;
            margin: 2rem 0;
        }

        .status-message {
            padding: 1rem;
            border-radius: 6px;
            margin: 1rem 0;
            text-align: center;
        }

        .success { background: #e8f5e9; color: var(--success); }
        .warning { background: #fff3e0; color: var(--warning); }
        .error { background: #ffebee; color: var(--danger); }