As I had opted for a free theme there were the expected minor bugs that aren't too noticeable but one really annoyed me as it was right at a focal point of the site. Through some investigating I found that the spacing of the widgets in the sidebar had been given padding value that created a really ugly and uneven spacing when using the style properties I chose.
To get around this problem I used a very helpful part of the Jetpack package of plug-ins I installed- the CSS Editor. This feature adds CSS in after the existing code which means it just over-writes any rules in place already, reducing the risk of adding in problems by accident. Using this I added several rules in to correct the problem, using Firefox's inspector to check along the way.