body
{
font-family:Georgia;
text-align:center;
}

header 
{
padding: 60px;
text-align: left;
background: #1abc9c;
color: white;
font-size: 30px;
}

.button {
  background-color: #151B54;
  border: none;
  color: white;
  padding: 15px 32px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  margin: 4px 2px;
  cursor: pointer;
}

a.header:link{
color:black;
text-decoration: none;
}

a.header:visited
{
color:black;
text-decoration:none;
}

a.header:hover {
color:#808080;
text-decoration: none;
}

a.footer:link{
color:white;
text-decoration: none;
}

a.footer:visited
{
color:white;
text-decoration: none;
}

a.footer:hover
{
color:#808080;
text-decoration:none;
}

a.button:hover
{
background-color:#010740;
}

a.rect img
{
border:8px solid white;
}


a.rect:hover img
{
border:8px solid #151B54;
}

a.bluerect img{
border:8px solid white;
}

a.bluerect:hover img
{
border:10px solid white;
}

.container {
  position: relative;
  width: 100%;
  <!-- max-width: 400px; -->
}

.overlay {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  height: 100%;
  width: 100%;
  opacity: 0;
  transition: .5s ease;;
}

.container:hover .overlay {
  opacity: 1;
}

.center
{
<!-- display:block;
margin-left:auto;
margin-right:auto;
float:center;
-->
margin-left:auto;
margin-right:auto;
}