:root {
            --bg-color: #f5f5f5;
            --container-bg: #ffffff;
            --text-color: #333333;
            --button-bg: #4CAF50;
            --button-hover: #45a049;
            --shadow-color: rgba(0, 0, 0, 0.1);
            --border-color: #e0e0e0;
            --secondary-text: #666666;
        }

        [data-theme="dark"] {
            --bg-color: #121212;
            --container-bg: #1e1e1e;
            --text-color: #e0e0e0;
            --button-bg: #2e7d32;
            --button-hover: #1b5e20;
            --shadow-color: rgba(0, 0, 0, 0.3);
            --border-color: #333333;
            --secondary-text: #888888;
        }

        * {
            box-sizing: border-box;
            transition: background-color 0.3s, color 0.3s, border-color 0.3s;
        }

        body {
            font-family: Arial, sans-serif;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
            margin: 0;
            padding: 20px;
            background-color: var(--bg-color);
            color: var(--text-color);
        }

        .index-container {
            background-color: var(--container-bg);
            padding: 30px;
            border-radius: 12px;
            box-shadow: 0 4px 20px var(--shadow-color);
            text-align: center;
            width: 100%;
            max-width: 400px;
            position: relative;
            border: 1px solid var(--border-color);
        }

        h1 {
            color: var(--text-color);
            margin: 0 0 20px;
            font-size: 24px;
        }

        .button-group {
            display: flex;
            flex-direction: column;
            gap: 15px;
            margin-top: 25px;
        }

        button {
            padding: 12px;
            background-color: var(--button-bg);
            color: white;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            font-size: 16px;
            font-weight: 500;
            transition: transform 0.2s, background-color 0.3s;
        }

        button:hover {
            background-color: var(--button-hover);
            transform: translateY(-1px);
        }

        button:active {
            transform: translateY(0);
        }

        .copyright {
            color: var(--secondary-text);
            font-size: 12px;
            margin: 20px 0 0;
        }

        .theme-toggle {
            position: absolute;
            top: 20px;
            right: 20px;
            background: none;
            border: none;
            font-size: 20px;
            cursor: pointer;
            color: var(--text-color);
            opacity: 0.7;
            padding: 5px;
            border-radius: 50%;
        }

        .theme-toggle:hover {
            opacity: 1;
            background-color: rgba(0, 0, 0, 0.1);
        }

        @media (max-width: 480px) {
            .index-container {
                padding: 20px;
                border-radius: 8px;
            }

            h1 {
                font-size: 20px;
            }

            button {
                padding: 10px;
                font-size: 15px;
            }
        }