/* CSS some parts help taken from w3school*/
<style>
html{
   min-height: 100%;
}
body {margin:0; 

}

ul {
  z-index: 1;
  list-style-type: none;
  margin: 0;
  margin-left: 0px;
  padding: 0;
  overflow: hidden;
  background-color: #ffffff;
  position: fixed;
  top: 0;
  width: 100%;
}

li {
  float: left;

}

li a {
  display: block;
  color: gray;
  text-align: center;
  padding: 16px 18px;
  text-decoration: none;
  font-size: 16pt;
  font-family:sans-serif  ;
}

li a:hover:not(.active) {
  color: black;
}

.active {
  color: black;
}
img {
  filter: grayscale(100%);
}
/**/

</style>