body {
}
#container {
  width: 800px;
  margin:50px auto;
}
.header, .nav, .col, .footer {
  float: left;
}
.header {
  width: 800px;
  height: 100px;
  margin: 0 0 10px;
  background-color: red;
}
.nav {
  width: 800px;
  height: 50px;
  margin: 0 0 10px;
  background-color: red;
}
.col {
  width: calc(780px / 3);
  height: 1000px;
 float: left;
 margin-bottom: 10px;
  background-color: red;
}
.margin{
  margin: 0 10px 0 0;
}
.footer{
  width: 100%;
  height: 100px;
  background-color: red;
  margin-right {margin: 0 10px 0 0;}
}