Sidebar content cut off with magnification

[streats]

When using a lower resolution
(e.g. 1024 x 640) and/or browser zoom (e.g. 125%), the left sidebar content is cut off at the top. This introduces usability and accessibility issues as it makes the site less usable by people who use magnification. I have only basic CSS knowledge and am new to Jekyll so
I'm unsure how to fix this myself, but it would be advisable to have this fixed in the out-of-the-box theme.