body {
  background-color:#FFFFFF;
  color:black;
  filter: grayscale(1);
  background: whitesmoke;
}

main {
  margin-left:auto;
  margin-right:auto;
  max-width:600px;
  border: solid 2px;
  padding:20px
    
}

img {
  max-width: 100%;
}

img::hover {
  filter: invert(100%);
}

footer {
  background-color:black;
  color:white;
  padding; 10px;
  width: 100%;
  text-align:center;
}