body {
    margin: 0; /* quitar margen superior de 20px */
    font-family: Arial, sans-serif;
    background-color: burlywood;
}

.content {
    width: 80%;
    max-width: 800px; /* opcional, para que no se estire demasiado */
    margin: 20px auto; /* centrado horizontal y margen superior */
    padding: 20px;
    box-sizing: border-box;
    background-color: antiquewhite;
    border-radius: 10px;
}



        h1 {
            font-size: 2em;
            margin-bottom: 20px;
        }
       #timer {
    font-size: 6em;
    margin-bottom: 20px;
  
    color: brown;
    text-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
    background: linear-gradient(135deg, #ff7e5f, #feb47b);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    border: 5px solid rgba(255, 255, 255, 0.2);
    padding: 20px;
    border-radius: 20px;
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.3);
    animation: glow 1.5s infinite alternate;
}
        button {
            font-size: 1em;
            padding: 10px 20px;
            margin: 5px;
            border: none;
            border-radius: 5px;
            cursor: pointer;
        }
        .start {
            background-color: #4CAF50;
            color: white;
        }
        .reset {
            background-color: #f44336;
            color: white;
        }
        .break {
            background-color: #2196F3;
            color: white;
        }
        .card {
            padding: 10px;
            margin: 5px;
            border: 1px solid #ccc;
            border-radius: 5px;
            background: #fff;
            cursor: pointer;
            transition: background 0.3s ease;
        }
        .card:hover {
            background: #f0f0f0;
        }
        .card.selected {
            background: #4CAF50;
            color: white;
        }
        .custom-alert {
            position: fixed;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            padding: 20px;
            background-color: white;
            border: 2px solid black;
            z-index: 1000;
            box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.5);
        }
        .custom-alert button {
            margin-top: 10px;
        }
        iframe {
            width: 0%;
            height: 100%;
            border: none;
        }