changing the screen width at which nav and toc are hidden

[odisfm]

using a 13" macbook with the default 1400x900 scaling and vertical tabs in browser, the left nav disappears way too quickly for my tastes. due to the nature of my content, I'd prefer to lose a lot more width from the main 'article' element before the nav and toc disappear to make room.

I've tried messing with the css to no avail. thinking maybe this is being done in js?

any pointers are greatly appreciated 🙏