The Enhanced/Legacy Experience Code just needs to be wrapped in a DIV with max-width styling – for example:
<div id="zmagsWrapper" style="max-width:1260px; margin: 0 auto">
PASTE ENHANCED/LEGACY CODE HERE
The max-width property lets you set the size (in pixels) for how wide the Experience should be and the “margin: 0 auto” code will center it on your page.
Please contact email@example.com with any further questions on this!