:root {
            --primary-color: #2c3e50;
            --accent-color: #3498db;
            --bg-color: #f4f7f6;
            --text-color: #333;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            color: var(--text-color);
            background-color: var(--bg-color);
            margin: 0;
            padding: 0;
        }

        header {
            background: var(--primary-color);
            color: white;
            padding: 2rem 1rem;
            text-align: center;
        }

        /* .container {
            max-width: 900px;
            margin: 2rem auto;
            padding: 0 1rem;
        } */

        .intro {
            background: white;
            padding: 2rem;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            margin-bottom: 2rem;
        }

        .timeline {
            position: relative;
            padding: 1rem 0;
        }

        .timeline::before {
            content: '';
            position: absolute;
            width: 4px;
            background: var(--accent-color);
            top: 0;
            bottom: 0;
            left: 50%;
            margin-left: -2px;
        }

        .era-title {
            text-align: center;
            background: var(--accent-color);
            color: white;
            padding: 0.5rem 1rem;
            border-radius: 20px;
            width: fit-content;
            margin: 2rem auto;
            position: relative;
            z-index: 1;
        }

        .event {
            padding: 1rem 2rem;
            position: relative;
            background: white;
            width: 40%;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            margin-bottom: 2rem;
        }

        .event.left { left: 0; }
        .event.right { left: 55%; }

        .date {
            font-weight: bold;
            color: var(--accent-color);
            display: block;
            font-size: 1.2rem;
            margin-bottom: 0.5rem;
        }

        footer {
            text-align: center;
            padding: 2rem;
            font-size: 0.9rem;
            color: #666;
        }