Extremely inconsistent font sizes--tiny on page and huge in textboxes

Hello, I am running Firefox 23 on Slackware Linux. My computer is an ultrabook with an relatively small, high resolution screen, so I have had to set a high dpi (190) to get font sizes rendered appropriately. The value of 190 was obtained by calculating the proper value for my screen size and resolution (11.3 inches; 1900 x 1080), and in most circumstances, everything looks good. However, in Firefox, my fonts are extremely tiny. I have installed an add-on No-Squint to set the default zoom level of every page to 170 %, which works well. However, this results in normal (or even rather small) page fonts, while the fonts in textboxes (like password fields, select-some-value boxes, etc.) are enormous. It seems like the fonts in the textboxes are respecting my dpi value, while the rest of the fonts on the page are not. This means that when the page is zoomed in, the textbox fonts look huge. What I need is a way to make Firefox either respect my system dpi everywhere or nowhere. I have tried changing the values for layout.css.devPixelsPerPx, and it makes no difference. Thanks for any help.