For blockquotes I personally favor a small 3px border-left thats preferably colored. It provides a clear visual separation from the main content and most people are accustomed to seeing a border-left as a quote from their usage in email reply’s (quote level).

Here’s a link to one article on my blog as an example:

https://tardis.digital/article/i-fucked-up

The lead ins are really hard to read: different font-size + capitals + not clear how they are chosen. I would just remove them.

h3 seems to similar to body text. Maybe because the top and bottom margin is almost identical

Maybe reduce/remove the paragraph gaps inside the block quotes and brighten up the citation.

Unfortunately, I cannot give you any tips, because my practical design skills are non-existent.

For my own web site I gave up for the time being and am living with DokuWiki's default theme. But I'm planning to give it another try over Easter.