Hello! Thanks for your interest to the ExS theme.
Box layout is implemented as one of predefined CSS skins in the PRO version.
However you can easily create it in a free version with a small CSS snippet that you can add in your theme Customizer -> Additional CSS section:
body{
background-color: #fafafa;
}
#box{
max-width: 1400px;
margin: 0 auto;
background-color: #ffffff;
box-shadow: 0 0 100px 0 rgba(100, 100, 100, 0.15);
}
@media screen and (max-width: 1420px) {
#box{
margin-left: 15px;
margin-right: 15px;
}
}
Hope this helps.
Best regards!