Hi there,
Unfortunately, our theme does not have such a feature. You can use custom CSS code to somehow try to have the same functionality, but then you will lose all the settings of the theme and the CSS will override them on mobile. And it might have bugs here and there as the fact is we are trying to force our way into the boxed layout with custom CSS.
Having said that you can try this code by adding it to X > Launch > Options > CSS:
@media (max-width: 767px) {
#top.site {
max-width: 1170px;
-webkit-flex: 1 1 auto;
flex: 1 1 auto;
position: relative;
width: 100%;
min-width: 1px;
border: 1px solid rgba(0,0,0,0.275);
border-top: 0;
border-bottom: 0;
background-color: #fff;
box-shadow: 0 0 5px rgba(0,0,0,0.125);
box-sizing: content-box;
}
.x-root {
justify-content: center;
}
}
The code above will force a boxed layout for devices which have the browser width of 767 pixels or smaller.
The code above is not part of our support scope and is just an extra try to be as helpful as we can.
Thank you.