M2 CSS tricks, applying PADDING

I've tried everything but after achieving the result, rest of the site is a smush.

Membership2 Registration page opens a separete, pop-up type pageview which doesn't follow the rest of the site. I've tried to trigger just the div id but still the very simple padding round the page seems to be impossible to achieve and the page shows the text starting from the very edge – not looking nice at all. Please help.

I'm using the Elegant Themes Divi -theme which is quite popular one out there. Since the CSS doesn't trigger on the M2 pop-up type pageviews, I use Child Theme and it works on other CSS adjustments but not this one.

I'm simply trying to accomplish a padding around the content of the this page.