* { box-sizing: border-box;}

body {font-family: Arial, Helvetica, sans-serif;}

header { background-color: rgb(102,51,204);; padding: 30px; text-align: center; font-size: 35px; color: red ;}

nav { float: left; width: 30%; height: 3000px; background: #ccc; padding: 20px;}

nav ul{list-style-type: none; padding: 0 ;}

article {float: left;padding: 20px; width: 70%; background-color: rgb(153,204,0); ; height: 3000px; }

section::after {content:""; display: table; clear: both;}

footer { background-color: rgb(255,102,255); padding: 10px; text-align: center; color: white }

@media (max-width: 600px) {nav,article {width: 100%; height:auto;}}