css

body{
    margin: 0px;
}


header{
    background-color: black;
    font-size: 24px;
    color: white;


}

#nav1 {
    border: 1px black outset;
    margin-top: 10px;
    margin-bottom: 20px;
    width: 19%;
    float: left;
    font-size: 28px;

}

#nav2 {
    border: 1px black outset;
    margin-top: 10px;
    margin-bottom: 20px;
    width: 19%;
    float: left;
    font-size:28px;
}

#content{
    margin-top:10px;
    float: left;
    width: 60%;
    font-size: 28px;
}

@media screen and (max-width: 400px){
    body{
        margin:0 auto;
    }

    #nav1{
        width:100%;
        font-size:20px;

           }
    #nav2{
        width:100%;
        font-size:20px;
    }
    #content{
        width:100%;
        font-size:20px;

    }

}