body {
  background-color: white;
  font-size: normal;
  width: 90%;
}

div.header, div.footer {
  background-color: silver;
}

div.topmenu {
  background-color: #90ee90;   <!-- lightgreen -->
  border-style: ridge;
  margin-right: 1cm;
  float: left;
  width: 100%
}

div.topmain {
  margin-left: 1cm;
  margin-bottom: 1cm;
}

div.main {
  margin-left: 1cm;
}

div.box {
  border-color: aqua;
  border-style: solid;
}