ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #333;
  
    position: fixed;
  top: 40px;
  width: 100%;
}

li {
  float: left;
}

li a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

/* Change the link color to #111 (black) on hover */
li a:hover {
  background-color: #111;
}

header{
	 background-image: linear-gradient(to right, red , yellow);
	     position: fixed;
  top: 0px;
  width: 100%;
  height: 40px;
}
header h1{
	margin:0px;
}

article{
	margin-top:100px;
	margin-bottom: 30px;
	margin-left: 10px;
	margin-right: 10px;
	
}

footer{
	 position: fixed;
  bottom: 0;
  width: 100%;
  background-color: Green;
}

body{
	margin: 0px;
}