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

        body {
            font-family: Arial, sans-serif;
            background-color: #f5f5f5;
            height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        .container {
            width: 100%;
            max-width: 400px;
            padding: 20px;
        }

        .timer-box {
            background: white;
            border-radius: 10px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            padding: 30px;
            text-align: center;
        }

        h1 {
            color: #333;
            margin-bottom: 20px;
            font-size: 24px;
        }

        .timer-display {
            font-size: 48px;
            font-weight: bold;
            color: #e74c3c;
            margin: 20px 0;
            font-family: monospace;
        }

        .controls {
            margin: 25px 0;
        }

        .btn {
            border: none;
            padding: 12px 20px;
            margin: 0 5px;
            border-radius: 5px;
            cursor: pointer;
            font-size: 16px;
            font-weight: bold;
            transition: background-color 0.3s;
        }

        .btn:hover {
            opacity: 0.9;
        }

        .primary {
            background-color: #27ae60;
            color: white;
        }

        .secondary {
            background-color: #e74c3c;
            color: white;
        }

        .tertiary {
            background-color: #95a5a6;
            color: white;
        }

        .status {
            margin-top: 20px;
        }

        #status-text {
            color: #666;
            font-size: 14px;
            font-style: italic;
        }