How do I set Button font larger than default, then scale it?

My game is heavily button based (glorified calculator), and it also requires user text-input via textbox. I know I can use sprites as buttons, but with the hundreds of buttons I'll be using, it's easier to use the built-in feature for now.

HOWEVER, The default CSS text-size is too small for my high resolution screen. I want the text on the buttons and textboxes to be larger, while also scaling with the user's window. I've tried all combinations of "auto-scale" properties and CSS screwing around, and it seems there's no way. Is there a way to change the CSS default-size font in textboxes, while also keeping auto-scale on? Or, if I want a giant "OK" button in the middle of the screen with big text, how can I keep it scaleable? Please help!

Disappointed there haven't been any responses to this question, as I'm having a similar problem. I shared my game with friends and found that the button text sometimes fits in the button boundary and sometimes doesn't, depending on their browser and screen size. The Auto font size option seems to be useless, since it might scale to the layout size, but it doesn't scale to the button size (as my friend notes above).

Websites seem to do this all the time, so how do you make a larger button with larger text whose text also scales?