To solve this issue, it looks like the problem may stem from how the CMS handles iframes and styling within a hosted environment compared to your local setup. One possible solution is to check if there are any restrictions or overrides applied by the CMS to iframe elements or external stylesheets. You might also want to inspect the iframe's embedded styles to ensure they aren’t being blocked or altered by the CMS environment. Lastly, double-check if the correct permissions and configurations for external content (such as iframes) are applied across the environments ('CI' and 'UAT').