body {
  background-color: white;
  color: black;
  font-family: Verdana;
}
.header {
  background-color: green;
  padding: 15px;
  text-align: center;
}
.header h2 {
  color: white;
  margin: 0;
}
.nav_menu {
  overflow: hidden;
  background-color: #333;
}
.nav_menu a {
  float: left;
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}
.nav_menu a:hover {
  background-color: white;
  color: green;
}
.sidebar,
.main {
  text-align: center;
  color: green;
}
.sidebar {
  width: 30%;
}
.main {
  width:70%;
}
.footer {
  background-color: green;
  padding: 15px;
  text-align: center;
}