@import url(https://fonts.googleapis.com/css?family=Exo:400,600,900);

* {
    font-family: "Exo", sans-serif;
    font-weight: 600;
    margin:0;
    padding: 0;
    box-sizing: border-box;
}

#pagina {
    width: 0 auto;
    max-width: 100%;
    background-attachment: fixed;
    background-size: auto;
}

header {
    background-color:rgba(0,0,0,0.8);
    padding-top: 1em;
    position: fixed;
    width: 100%;
}

header h1 {
    color: white;
    text-align: center;
    
}

header nav {
    color: white;
    font-family: "Exo", sans-serif;
    font-size: 0.9em;
    text-align: center;
    margin: 1em 0.5em;
}

header nav ul li {
    display: inline-block;
    margin: 0;
    padding: 0;
}

header nav ul li a {
    color: white;
    text-decoration: none;
    text-align: center;
    margin: 0.5em;   
    width: 100%;
    
}

main {
    overflow: auto;
    padding-top: 11em;
}

main img {
    width: 80%;
    margin: 0 10%;
    border-color: black;
    border-width: 1em;
    border-style: groove;
    box-shadow: 0.3em 0.3em 1em #222;
}

h2 {
    margin: 0 2em;
    margin-top: 1.5em;
    margin-bottom: 0.5em;
    text-align: center;
    font-size: 1.1em;
}

article {
    width: 80%;
    margin: 0 auto;
    margin-top: 2em;
    border-top: 0.2em;
    border-top-color: black;
    border-top-style: groove;
    padding: 1em 0;
}

article p {
    font-size: 0.9em;
    font-weight: 400;
    line-height: 1.5em;
    text-indent: 1.5em;
}


footer {
    margin-top: 3em;
    padding: 2em 3em;
    font-size: 0.8em;
    text-align: center;
    border-top: 5px;
    border-top-style: groove;
    border-color: black;
}

footer p {
    font-size: 0.8em;
}


@media screen and (min-width:55em){
    
    #pagina {
        background-attachment:scroll;
        height: 65em;
    }
    
    header nav ul li {
        padding: 0 1.5em;
    }
    
    main {
        width: 100%;
    }
    
    h2 {
        margin-bottom: 0.5em;
    }
    
    main img {
        box-shadow: 0.3em 0.3em 1em #222;
        border-width: 0.8em;
    }

    section {
        float:left;
        width: 25%;
        margin: 0;
        padding: 0 0 1em 0 ;
    }
    
    article {
    width: 50%;
    margin: 0 auto;
    margin-top: 1em;
    border: none;
    padding: 0;
}

article p {
    font-size: 0.9em;
    font-weight: 400;
    line-height: 1.5em;
    text-indent: 1.5em;
}
    
    footer {
        overflow: auto;
        clear: both;
        margin-top: 13em;
    }
    
    footer p {
        width: 70%;
        margin: 0 auto;
    }
    
    .boton {
        margin-top: 2em;
    }