styles.css

*{
    font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
}

body{
    margin: 0;
    background-image: url(img/fondo.jpg);
    background-repeat: repeat-y;
    background-attachment: scroll;
    background-size: cover;
}

#divPrincipal{
    display: grid;
    grid-template-areas: 
    'cabecera cabecera' 
    'contenido lateral'
    'footer footer';
    grid-template-columns: auto 20%;
    grid-template-rows: 15% auto 5%;
    height: 100vh;
    color: white;
}

#divCabecera{
    grid-area: cabecera;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: rgba(0, 0, 0, 0.8);
    font-size: 40px;
}

#divContenido{
    grid-area: contenido;
    border: 1px solid #68757B;
    padding-left: 2%;
    padding-right: 2%;
    margin: 10px;
    border-radius: 20px;
    background-color: rgba(0, 0, 0, 0.7);
}

#numero{
    font-family: monospace;
    font-size: 20px;
    width: 99.7%;
    resize: none;
    border-style: none;
    background-color: transparent;
    color: white;
}

#divTexto{
    font-family: monospace;
    font-size: 24px;
    width: 100%;
    height: auto;
}

#divLateral{
    grid-area: lateral;
    border: 1px solid #68757B;
    padding-left: 2%;
    padding-right: 2%;
    margin: 10px 10px 10px 0px;
    border-radius: 20px;
    background-color: rgba(0, 0, 0, 0.7);
}

#divFooter{
    grid-area: footer;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #68757B;
    font-size: 20px;
}

h2{
    font-size: 30px;
}

@media screen and (max-width: 900px){
    #divPrincipal{
        grid-template-areas: 
        'cabecera' 
        'contenido'
        'lateral'
        'footer';
        grid-template-columns: auto;
        grid-template-rows: 80px auto auto 5%;
        height: 100vh;
    }

    #divCabecera{
        font-size: 30px;
    }

    #divTexto{
        font-size: 20px;
    }

    #divLateral{
        margin: 0px 10px 10px;
    }

    p{
        font-size: 20px;
    }
}

@media screen and (max-width: 600px){
    #divPrincipal{
        grid-template-areas: 
        'cabecera' 
        'contenido'
        'lateral'
        'footer';
        grid-template-columns: auto;
        grid-template-rows: 65px auto auto 5%;
        height: 100vh;
    }

    #divCabecera{
        font-size: 15px;
    }
    
    p{
        font-size: 15px;
    }
}