Web sites vary as to whether they enforce a maximum width for the content within the window. When running Safari full screen on Lion, is there a simple way (without rolling up my sleeves and playing with style sheets) to establish my own maximum width? Lines of text are too long if I happen to be connected to my 24" monitor, but I like how this full screen mode maximizes vertical space.
You can change the width of each page in full-screen Safari.
Move your cursor all the way to either side of the 'window', until you see the normal window resize cursor. Click and drag in, and the 'window' will shrink horizontally.
You can set a different width for each tab.
If you would like to enforce a maximum width across all web sites permanently, you can use a user style sheet file (Safari Preferences → Advanced → Style sheet) with something like the following content:
Nathan's answer is probably more useful, but this is how you could do it if they hadn't included the resizing feature.
(This has a chance of breaking the layout of any web site that's using the same approach to set up a smaller column width than you asked for.)