body {
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(to bottom right, #ff9a8b, #e6ccd1, #ff99ac);
}

.ficha {
    width: 250px;
    background: white;
    border-radius: 10px;
    box-shadow: 0px 0px 10px gray;
    text-align: center;
    padding: 20px;
    position: relative;
}

.encabezado {
    background: red;
    height: 30px;
    width: 100%;
    position: absolute;
    top: 0;
    left: 0;
}

.operacion {
    margin-top: 50px;
    font-size: 2rem;
    font-weight: bold;
}

.numero {
    display: block;
}

.multiplicacion {
    display: block;
    margin: 5px 0;
}

.linea {
    width: 50px;
    height: 2px;
    background: black;
    margin: 5px auto;
}

.respuesta {
    display: none;
    font-size: 2rem;
    font-weight: bold;
    margin-top: 5px;
}

#opciones {
    margin-top: 10px;
}

.opcion {
    display: inline-block;
    margin: 5px;
    padding: 10px;
    background-color: lightblue;
    cursor: pointer;
    border-radius: 5px;
}

.opcion:hover {
    background-color: deepskyblue;
}

#mensaje {
    margin-top: 10px;
    font-size: 1.2rem;
}

#cuadricula {
    margin-top: 10px;
    display: none;
}

table {
    width: 100%;
    border-collapse: collapse;
}

td {
    width: 10%;
    height: 10px;
    border: 1px solid gray;
}

.oculto {
    display: none;
}