kyber

the list item font change confuses me somewhat; strictly, unless you have put line breaks in, it should all appear in the same line anyway; looking at the inspect element details in chrome, there is some very odd formatting going on

always a bit iffy having mutiple lines on list elements, I think perhaps another block type might be more suitable

interesting though

I only recently started using this theme and have only just had chance to have a play today – have not played with CSS for years.

I have just had a quick look at the css file, and I see:

.entry-content p, .entry-content li, .entry-content dt, .entry-content dd {font-size:1.6em; margin-bottom:.75em;}
It looks like this sets the text content a little larger than the base. I can see no setting to change the default font size for a div within the entry-content block (or indeed for div generally).

You need to either add a css line for div in the entry block, or code the posts in a more compliant manner:
<div>this is some text</div
should be:
<div><p>this is some text</p></div>

You need theme switcher code or a plugin. A google will provide, but you will probably find this a good place to start: wordpress article on theme switching.

However, I suspect the dark/light schemes are exactly the same theme with a simple CSS tweak. Look at the css file in the admin panel to see, you can include some very simple php code to set the appropriate switch I am sure.