body { font-family: sans-serif; margin: 0; }

.header {
  text-align: center; 
  font-size: 20px;
  padding: 80px;
  background-color: darkcyan;
  color: white;
}

.main {
  display: flex
  font-size: 24px;
}

.left {
  flex: 1;
  padding: 20px;
  border: 1px black;
  margin: 10px;
}

.right {
  flex: 3;
  padding: 20px;
  border: 1px black;
  margin: 10px;
}

.navbar {
  background-color: #333;
  overflow: hidden;
}
.navbar a {
  float: left;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}
.navbar a:hover {
  background-color: orange;
  color: black;
}
.navbar a.active {
  background-color: Darkgreen;
  color: white;
}