* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
}

div {
  height: 100vh;
  margin: 0;
  padding: 0;
}

.inner {
  position: relative;
  width: 100%;
  float: right;
  margin-left: 0;
  margin-right: 0;
  clear: none;
}

.col {
  background: black;
  background-clip: content-box;
  padding-bottom: 20px;
  height: 25vh;
  color: white;
}
.col:nth-child(4n+1) {
  width: 25%;
  float: left;
  margin-right: -100%;
  clear: none;
  padding-right: 20px;
  clear: left;
}
.col:nth-child(4n+2) {
  width: 25%;
  float: left;
  margin-right: -100%;
  margin-left: 25%;
  clear: none;
  padding-right: 20px;
}
.col:nth-child(4n+3) {
  width: 25%;
  float: left;
  margin-right: -100%;
  margin-left: 50%;
  clear: none;
  padding-right: 20px;
}
.col:nth-child(4n+4) {
  width: 25%;
  float: right;
  margin-left: 0;
  margin-right: 0;
  clear: none;
  padding-right: 0;
}

.main {
  width: -webkit-calc((((100% - (300px + 20px)) / (1))) * 1);
  width: calc((((100% - (300px + 20px)) / (1))) * 1);
  float: left;
  margin-right: -100%;
  margin-left: -webkit-calc((200px + 10px));
  margin-left: calc((200px + 10px));
  background: red;
}

.primary-sidebar {
  background: green;
  width: 200px;
  float: left;
  margin-right: -100%;
  margin-left: 0;
}

.secondary-sidebar {
  background: green;
  width: 100px;
  float: right;
  margin-left: 0;
  margin-right: 0;
}