There is a good help doc article that explains the pros/cons of AA, AAM/Shared Audience, and Target.  Please refer to the link below:Audience creation options in Adobe Experience Cloud

Hi hayley1989,Not sure if you've managed to fix the issue, but in case you are still facing the same issue, you may want to palce the CSS code within the style tag within the Custom Code section.  E.g.,<style>.example {     overflow: hidden !important;     position: relative !important;     backgrou...