Desktop - that's my complaint... you wrote that the code samples "barely fit on desktop", which is only true because your CSS wastes over 2/3rds of the screen width I have provided to my user agent.
(it's fine though - I use Reader Mode on such user-hostile sites)
I'm struggling to find a width for the layout that makes sense for text (where narrow columns are preferable), but also for code snippets (where you want wider columns).
You may be overthinking it - most blogs simply allow the text to be the width of the window... your article is very readable in Firefox's Reader Mode, so for what it's worth, my $0.02 is that'd be fine
