To make Firefox bigger (maybe Thunderbird?)
Go into:
~/.mozilla/firefox/default.15t/chrome
And use the below to compare with your "userChrome.css" file
* {
font-size: 12pt !important;
font-family:Bitstream Vera Serif
}
menupopup > * {
font-size: 20pt !important
}
Those are my settings.
hth
/d