Often the page font is too small; rarely it’s too large. To fix this, while viewing the page …
To enlarge the font, click .
To shrink the font, click .
Repeat above until the size is right
Note: this does not stick; viewing another page reverts to its default font size.
Generic Sans-Serif, Serif, and Monospace Fonts
The Firefox idiots only made it possible to easily (reasonably) customize the generic sans-serif,
serif, and monospace fonts. In Firefox …
Click on Tools, Settings, General,
scroll down to Language and Appearance, and click on .
Select among the fonts and font sizes listed.
Generic Cursive Font
The Firefox idiots made it hard to customize the generic cursive font. In Firefox,
for western (Latin) fonts …
Enter the pseudo address about:config.
Click the button .
Enter font.name.cursive.x-western to see the current western generic cursive font name.
Enter the name of the font desired.
Generic Fantasy Font
The Firefox idiots made it even harder to customize the generic fantasy font. In Firefox,
for western (Latin) fonts …
Enter the pseudo address about:config.
Click the button .
Enter font.name.fantasy.x-western to see the current western generic fantasy font name (if any):
If a there is already a fantasy font configured, enter the name of the desired font.
If, however, b there is not already a fantasy font configured, click on the String radio button, click on ➕,
and enter the name of the font desired.
Customizing Mozilla Thumderbird
This tells how to customize the Thunderbird eMail/newsreader app: