Import a site ( or a part of a site) to Oxygen using Nimbufy. https://permaslug.com/clone-your-site-to-oxygen-using-nimbufy/
Two options to solve this problem
When adding images to posts using the classic editor. The images will not be responsive. Do this. Open posts template > click on the div that has the images on it > click style output > right at the bottom you will see the "img" tag > hightlight that > go to advanced > custom css> and past this in img width: 100%;height: auto; Please add this to your oxygen css as standard, do all images added in classic editor are responsive by default.
How to fix the white space: https://permaslug.com/fix-white-space-on-right-side-on-mobile-in-oxygen/#:~:text=Finding%20yourself%20with%20white%20space,Oxygen%20page%20on%20mobile%20devices%3F&text=This%20issue%20is%20usually%20caused,breakpoint%20to%20make%20it%20fit.
If you cannot know where the problManualem is: https://oxygen4fun.supadezign.com/tips/how-to-fix-the-gap-problem-on-mobile-view/