In browser based games many of the fonts supported on C2 will not appear in the correct location on a different browser.
Firefox and Chrome and other browsers use different font parameters. Probably because they compete with each other.
Some fonts like Bookman old style are pretty universal and will appear the same on any browser.
Text fonts are actually copyrighted and unless released into public domain browsers and mobile systems have to pay royalties to the font owner to support that font on their systems. Too avoid that extra cost they limit their font support to universal fonts.
So you can either use a univeral font or use sprite fonts and make your own or I use some of the free online text makers to create buttons and text sprites.
You can find button and text makers all over but I use this one a lot: