If you are linux u can simply press "shift-ctrl-+"

Thanks for yopur quick rfeply. Unfortunately it did not work. I have a new MacBook Air running macos Sequoia 15.3

Not sure Ctrl (w/ or w/o Shft) + scroll mouse will adjust Fx bookmarks library (doesn't in my linux). Don't think Settings / General tab / Fonts > Advanced, & changing either 'main' or min. font size on bookmarks library (didn't here). https://connect.mozilla.org/t5/discussions/bookmark-font-size/td-p/53131 https://forums.mozillazine.org/viewtopic.php?p=14854921 an old one this forum: https://support.mozilla.org/en-US/questions/1017600 May need to find newer post, to get correct CSS selector / property names for recent Fx versions.