.blue{
  background: blue;
}
.green{
  background: green;
}
.red{
  background: red;
}
.tall{
  height: 100%;
  padding-bottom:100%;
  margin-bottom: -100%;
}
.small-border{
  border: 1px solid black;

}
.no-padding{
 padding-top: 0px;
padding-right: 0px;
padding-bottom: 0px;
padding-left: 0px; 
}
.no-overflow{
overflow:hidden;
}