body{
    margin:auto;
    ;
    width: 1224px;
}

header{
    width: 1200px; /* 100% */
    height: 200px;
}

nav, article, aside{
    height:500px;
    border: 1px solid none;
   
}

nav{
    width: 200px;
    float: left;
    background-color: rgb(148,187,233,1);
}
    
article{
    width: 1000px;
    float: left;
    overflow: auto;
    background: radial-gradient(circle, rgba(238,174,202,1) 0%, rgba(148,187,233,1) 100%);
}
    
aside{
    width: 224px;
    float: left;
}

*{box-sizing: border-box
}

body > footer{
    border: 5px dotted blue;
    height: 200px;
    clear: both;
}

iframe{
    width: 100%;
    height: 100%;
    border: none;
}

body>footer, body>nav, body>article{
    padding: 15px;
}