#header {
  background-color:black;
  color:white;
  text-align:center;
  padding:5px;
}

#nav {
  line-height:30px;
  background-color:#eeeeee;
  height:300px;
  width:100px;
  float:left;
  padding:5px;
  text-align: center;
}

#section {
  font-family: Roboto
  width:350px;
  float:left;
  padding:10px;
}

#footer {
  font-family: Roboto
  background-color: black;
  color: white;
  clear:both;
  text-align:center;
  padding:5px;
}

a {
  color: inherit;
}
#header {
  background-color:black;
  color:white;
  text-align:center;
  padding:5px;
}

#nav {
  line-height:30px;
  background-color:#eeeeee;
  height:300px;
  width:100px;
  float:left;
  padding:5px;
  text-align: center;
}

#section {
  font-family: Roboto
  width:350px;
  float:left;
  padding:10px;
}

#footer {
  font-family: Roboto;
  background-color: black;
  color: white;
  clear:both;
  text-align:center;
  height: 5em;
  width: 100%;
}

a {
  color: inherit;
}
Fix footer background-color, add width, height
Fix footer background-color, add width, height
