h1 {color:blue;}
@media screen and (max-width: 900px) {div.example {
    display: flex;  align-items: center;flex-direction: column;
  }}
Body{background-image:""}
@media screen and (min-width: 480px) {
  #leftsidebar {width: 200px; float: left;}
  #main {margin-left: 216px;}
}