body{
    width: 100%;
}
main {
    position: relative;
}
 .center{
    margin: 2em 10% 2em 10%;
    padding-left: auto;
    padding-right: auto;
    box-shadow: 0 .3em 1em #000;
} 
#content{
    display: block;
  margin-left: auto;
  margin-right: auto;
  width: 75%;
text-align: center;
    margin-top: 50px;
    margin-bottom: 50px;
    min-height: 600px;
}