header {background-image: url(stars.jpg);
color: white;
text-align: center;
font-size: 35px;
padding: 30px;
}

nav {
  float: left;
  width: 20%;
  height: 300px;
  background-color: #008080;
  padding: 20px;
}
nav ul{list-style-type: none;
padding: 0;}

nav a{text-decoration: none;
color: #FFFFFF}

main{ float: left;
  margin: 0;
  width: 70%;
  background-color: #FFFFFF;
  height: 300px;
  font-size: 95%}

footer {
  background-color: #00008B;
  padding: 10px;
  text-align: center;
  color: white;
}

a:hover {background-color: blue;}

.col-container{
	display:table;
	width: 100%;
	background-color: #ADD8E6}

.col{
display: table-cell;}

* {
  box-sizing: border-box;
}

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

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

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