ul.nav {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: black;
}

body{
	background-image: linear-gradient(blue, white);
	background-repeat: no-repeat;
	background-size: auto;
	}
li {
  float: left;
}

li a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 84px;
  text-decoration: none;
}

li a:hover {
  background-color: yellow;
  color: black;
}
</style>
</head>


<ul>
  <li><a class="active" href="#home">Home</a></li>
  <li><a href="#news">News</a></li>
  <li><a href="#contact">Contact</a></li>
  <li><a href="#about">About</a></li>
</ul>

p {
	position: relative;
	top: 300px;
}

h3 {
	position: absolute;
	top: 80px;
}

img.mySlides {
	display: block;
  margin-left: auto;
  margin-right: auto;
	height: 470px;
	width: 370px;
}

img.Slides {
	display: block;
  margin-left: auto;
  margin-right: auto;
	height: 370px;
	width: 470px;
}