I use NoSquint on Firefox. My setup is a 15.6" laptop screen about two feet from my face, and I have trouble reading small print at that distance. I set NoSquint to magnify text only, and not the whole layout, so as not to ruin things, but that itself ruins some layouts. Not usually on Dreamwidth, although the Nav bar runs off to the side and makes a horizontal scrollbar if I use normal Firefox zooming or have it zoom the whole layout.

... which is one reason why I switched to NoSquint.