Add margin to billing fields

[jacobherrington]

Really small, annoying style thing I noticed.

Before:

After:

[kennyadsl]

Thanks @jacobherrington! Why the margin change to the button?

[jacobherrington]

@kennyadsl I noticed it later and didn't want to make a separate PR.

The button is sitting at the very bottom of the page, it just adds a tiny amount of whitespace so that it's not against the bottom edge of the window.

[tvdeyen]

We should not address styling issues like this. More generic solutions are preferable. Otherwise the whole admin css getting more and more messier than it is already.

[jacobherrington]

@tvdeyen I agree with your comments, this was sloppy CSS, but I do think we should have a presentable UI. As long as we have best practices CSS is fairly easy to overwrite.

[jacobherrington]

@tvdeyen I updated the selector for adding margin to the billing field. The UI change is the same, but this is much more specific to this single element.

I looked for other places this CSS was needed and didn't find any, so I left the rules where they were. Please let me know if I need to do anything else for your approval.

Other changes have been requested

[kennyadsl]

@tvdeyen can you please review again?