@mreiter obsidian has the edit/live preview css structure and selectors differently than that of reading view. so you cannot simply exchange .markdown-source-view with .markdown-rendered. for reference, .HyperMD-list-line is somewhat a <ul> but not exactly.
this is one of the “pitfalls” of not following the best practices. empty lines are used to identify new paragraphs but since we only use single line break, it doesn’t create a <p> tag but simply insert a <br> tag.
at this point i’m gonna tap out (since doing a hack against the convention will be messy 
). my advice is to have those empty lines and use css just to tweak the reading view to be consistent with edit/live preview (similar to the post linked below).