body {background-color: gray;}
    div {
        background-color: gainsboro;
        width: 640px;
        max-width: 90%;
        margin: 10px auto 0px auto;
        padding: 20px;
        border: 10px;
    }
    
    h1 {
        color: cornflowerblue;
        font-family: Georgia, 'Times New Roman', Times, serif;
        padding: 20px;  
        border: 4px       
    } 
    h3 {
        font-family: Georgia, 'Times New Roman', Times, serif;
        background-color: gainsboro;
        padding: 20px;  
        border: 4px
    }
    p {
        font-family: Georgia, 'Times New Roman', Times, serif;
        color: black;
        font-size: 17px;
        padding: 20px;  
        border: 4px cornflowerblue;
        background-color: cornflowerblue;
    }
    p, a {font-family:Georgia, 'Times New Roman', Times, serif;}

    footer {
        color: blue;
        padding: 20px;  
        border: 4px;
        
    }


    header {
        border-bottom: 4px solid blue;
    }

    
    .adaptable {
        display: block;
        width: 100%;
        height: auto;
    }

    .italic {
        font-style: italic;
        background-color: cornflowerblue;
    }

    iframe {
        display: block;
        width: 80%;
        justify-content: center;
    }
    .encajonado {
        padding: 30px;
        text-align: center;
        background-color: gray;
    }