I am currently using Firefox (latest version – whatever that is) and Windows 7, my email is Virgin Media (webmail) and Gmail (my back-up email system).
My problem is – in my Blogger blog (my cat Frankie’s Mewspaper) and both web based email accounts – that I am unable to change the font or the size of the font. All the fonts are shown as looking the same.
I suspect that it is just that my PC shows the fonts as above but does actually change them. But it would be nice to see this actually happen.
One possibility - in Firefox you can go to the Tools menu, select Options, then the Content tab, and in the Fonts & Colors is the Advanced button (on the right of the first line) - click on that.
In the pop-up that you then see you can set what fonts are used and their sizes, AND there is a tick box for "allow pages to choose their own fonts, instead of my selection above". If you make sure that is unticked then the font sizes that you have selected will be used.
I knew that it was something to do with Firefox due to when it started. And I knew that it would be down to me tinkering where I shouldn't be tinkering.
I am off to help young Frankie update his Mewspaper! ;-)