Checkout: Tooltip Unreadable Due To Its Default Background

In my checkout, for some reason the text of the tooltip is white and the background of it is also white (with reduced opacity) by default, so it’s not very readable. Theme is Studio 11.0.

My shop is on the Basic plan so I know I can’t customize anything in the checkout… I’m just curious if I’ve got a colour scheme setting somewhere that is forcing the tooltip background to be so light. Does anyone know what “color scheme rules” (for lack of better words) the checkout obeys??

Theme editor: I have the “form fields” setting for the checkout set to white, but changing that to transparent doesn’t seem to do anything, so I guess those things aren’t related.

Branding: I don’t have anything remotely close to white set as a color so it can’t be that.

I’m at a loss. Any ideas?

Update: by fiddling with grey tones (for simplicity) I figured out that if the checkout’s “main content” section background colour is anything darker than #A6A6A6, its default text colour will automatically change to white, and that’s what the “order summary” section tooltip background colour relies on. So if the “content” text is white, the tooltip will background in the “summary” will switch from black to white, however the text will stay white. Annoying, so I’ll to let Shopify know that the text colour needs to automatically switch to black.