use the [[config editor]] to change the preference layout.css.devPixelsPerPx to 1.25 (125% of default) or 1.50 (150% of default).v Things can quickly become unworkable with this setting, so small increments is the best approach. ''<p>jayebird [[#question-1353180|said]]</p>'' <blockquote> I'm glad that on Reply pages I can set the font size I prefer. </blockquote> I am not, the people you are replying to are quite probably getting mail with fonts 10 feet tall on their machine. What you are setting is a size in pixels and that varies on each and every device. Anything over about 12 or 15 will look clownishly large to recipients.