:root {
            --primary-color: #3498db;
            --success-color: #2ecc71;
            --danger-color: #e74c3c;
            --warning-color: #f39c12;
            --text-color: #333;
            --bg-color: #f5f5f5;
            --card-bg: #fff;
            --border-radius: 8px;
            --box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        }
        
        body {
            font-family: 'Arial', sans-serif;
            line-height: 1.6;
            margin: 0;
            background-color: var(--bg-color);
            color: var(--text-color);
        }
        
        .container {
            max-width: 800px;
            margin: 20px auto;
            background-color: var(--card-bg);
            padding: 15px;
            border-radius: var(--border-radius);
            box-shadow: var(--box-shadow);
        }
        
        h1 {
            color: #2c3e50;
            text-align: center;
            margin-bottom: 20px;
            font-size: clamp(1.5rem, 4vw, 2rem);
        }
        
        .input-group {
            margin-bottom: 15px;
        }
        
        label {
            display: block;
            margin-bottom: 8px;
            font-weight: bold;
            font-size: clamp(0.9rem, 2vw, 1rem);
        }
        
        textarea {
            width: 100%;
            min-height: 100px;
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: 4px;
            resize: vertical;
            font-family: monospace;
            font-size: clamp(0.8rem, 2vw, 0.9rem);
            box-sizing: border-box;
        }
        
        .button-group {
            display: flex;
            gap: 10px;
            margin-bottom: 15px;
            flex-wrap: wrap;
        }
        
        button {
            padding: 12px 15px;
            color: white;
            border: none;
            border-radius: 6px;
            cursor: pointer;
            font-size: clamp(1rem, 3vw, 1.1rem);
            flex: 1 1 calc(33.333% - 10px);
            min-width: 100px;
            transition: all 0.3s;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
        }
        
        button:hover, button:active {
            opacity: 0.9;
            transform: translateY(-1px);
        }
        
        #encodeBtn {
            background-color: var(--primary-color);
        }
        
        #decodeBtn {
            background-color: var(--success-color);
        }
        
        #copyBtn {
            background-color: var(--warning-color);
        }
        
        #clearBtn {
            background-color: var(--danger-color);
        }
        
        .encoding-selector {
            margin-bottom: 15px;
            display: flex;
            flex-direction: column;
            gap: 8px;
        }
        
        .encoding-selector > span {
            font-weight: bold;
        }
        
        .radio-group {
            display: flex;
            gap: 15px;
        }
        
        .radio-option {
            display: flex;
            align-items: center;
            gap: 5px;
            font-size: clamp(0.9rem, 2vw, 1rem);
        }
        
        @media (max-width: 480px) {
            body {
                padding: 5px;
            }
            
            .container {
                padding: 10px;
            }
            
            .button-group {
                flex-direction: row;
                gap: 8px;
            }
            
            button {
                width: 100%;
                padding: 12px;
                flex: 1 1 calc(50% - 5px);
            }
            
            .radio-group {
                flex-direction: column;
                gap: 8px;
            }
            
            textarea {
                min-height: 80px;
            }
        }

        @media (max-width: 360px) {
            .button-group {
                flex-direction: column;
            }
            
            button {
                width: 100%;
                flex: 1 1 auto;
            }
        }