body {
  font-family:sans-serif;
}

h1 {
  margin: 5px 0;
}
h3 {
  margin:0;
  font-size:16px;
}
.demo {
  width:600px;
  height:120px;
  background-color:black;
  position:relative;
}

.box {
  width:50px;
  height:50px;
  position:relative;
  margin-bottom:2px;
}

.red {
  background-color:red;
}

.blue {
  background-color:blue;
}

.green {
  top:60px;
  left:25px;
  background-color:green;
}

.nav {
  width:600px;
  background-color:#ccc;
  text-align:right;
}

button {
  padding:10px;
  font-size:20px;
}