*{ box-sizing: border-box;}
body {
  font-family: Arial, Helvetica, sans-serif;}
#wrapper {
width: 80%;
  margin-left: auto;
  margin-right: auto;
  border: thin solid black;
  
  
}
header {
margin: 10px;
 padding: 10px;
  background-color: midnightblue;
  color: white;
}
nav {
    display: flex;
    justify-content: center;
}
nav > div {
    background-color:midnightblue;
    color:aliceblue;
    margin: 10px;
    padding: 10px;
    font-size: 20px;
  text-align: center;
flex: 1;
}
main {
    display: flex;
}
main > div {
    background-color:midnightblue;
    color:aliceblue;
    margin: 10px;
    padding: 10px;
}
.left {
    flex: 2;
}
.right {
    flex: 1;
}
footer {
background-color: midnightblue;
  margin: 10px;
  padding: 10px;
}

footer > p {
  text-align: center;
  color: white;
}
@media only screen and (max-width: 1024px) {
#wrapper {
  width: 100%;
  border: none;
  }
}


@media only screen and (max-width: 510px) {

    nav {
        flex-direction: column;
    }  
    nav > div {
        text-align: center;
      width: auto; 
      margin: 5px;
      
    } 
    main {
        flex-direction: column;
    }   
  main > div {
    margin: 5px;
  }
}