* {
  box-sizing: border-box;
}

body {
  background-color: #ccc;
  font-size: 12pt;
  font-family: 'rockwell', sans-serif;
  color: black;
}

header {
  padding: 5px;
  width: 100%;
  height: 10%;
  display: flex;
  align-items: center;
  justify-content: center;
  border-width: 5px 5px 5px 5px;
  border-style: solid;
  border-color: black;
  background-color: #888;
}

header li {
  list-style-type: none;
  padding: 5px;
  display: inline-block;
}

nav {
  float: left;
  padding: 10px;
  width: 10%;
  height: 80%;
  border-width: 0px 0px 5px 5px;
  border-style: solid;
  border-color: black;
  background-color: lightblue;
  overflow: auto;
}

nav ul {
  list-style-type: none;
  padding: 0;
}

article {
  float: left;
  padding: 20px;
  width: 80%;
  height: 80%;
  border-width: 0px 5px 5px 5px;
  border-style: solid;
  border-color: black;
  background-color: lightgreen;
  overflow: auto;
}

aside {
  float:left;
  padding: 10px;
  width: 10%;
  height: 80%;
  border-width: 0px 5px 5px 0px;
  border-style: solid;
  border-color: black;
  background-color: lightblue;
  overflow: auto;
}

aside ul {
  list-style-type: none;
  padding: 0;
}

footer {
  padding: 5px;
  width: 100%;
  height: 10%;
  display: flex;
  align-items: center;
  justify-content: center;
  border-width: 0px 5px 5px 5px;
  border-style: solid;
  border-color: black;
  background-color: #888;
}

footer li {
  list-style-type: none;
  padding: 5px;
  display: inline-block;
}

section::after {
  content: '';
}