Add this to userChrome.css:

.event-name-label{font-size: larger !important;}

Instead of 'larger' you can specify the size in pixels, e.g. 14px.

Sorry, but is there a category for this command in userChrome? Not sure how to enter full command....

Help/Troubleshooting Info, Profile Folder, Open Folder, close TB, create a new folder named chrome, create a new document in chrome with a text editor, name it userChrome.css, Save as type: All files *.*, copy in the above code, change the size as desired. Double-click toolkit.legacyUserProfileCustomizations.stylesheets to true in Settings/General/Config. editor, restart TB.

Online css generator

video on how to create a css file (Firefox and TB)

sfhowes: Sorry, I was not clear. Simply adding suggested line of code to userchrome does not work (also, do not see any other "." commands in my file). Could you perhaps paste any other coed lines that might enable that command?

Added the following to no avail (with comment line as reminder in future).....

/* Make calendar view default font size xx pt */ .event-name-label{font-size: 8 !important;}

It won't work with just 8; it has to be 8pt or 8px.

Ok, yes, was typo. Still no effect until I changed "larger" to "smaller" (which is what I wanted). Appears I must have another font style entry for overall font size in TB that would only allow the entry for size change vs specific font size. In any case, my monthly calendar view now has smaller event titles.....