How do MetaFilter display preferences work? Can I customize the fonts and background color?
Your Site Preferences let you choose a colored (default theme) or white (plain theme) background, and customize the size and font of different text types. You can use any font that's installed in your computer, just enter the name. (If a font name isn't working, try copying the exact name of the font as it appears in your computer's Fonts folder or library.) You can set the fonts to be bigger or smaller, and you can set any font size to 0 (zero) to remove that text from the display.
The defaults are these, in case you want to return to them after changing: Body Font - Verdana; Body Font Size - 10; Byline Font - Verdana; Byline Font Size - 8; Title Font - Arial; Title Font Size - 14.
When you click Save on your Site Preferences page, the display settings you chose are saved as cookies to your browser. That means you can have different display settings for different browsers. For example, you might use the default theme on your home computer, but the plain theme on your phone. Keep in mind that adjusting your display settings will change them for the browser you are currently using, but not other browsers. So if you want to update a particular display setting across all of the browsers you use, you'll need to re-save your display preferences on each of them. Be aware that saving your display preferences will make those settings the default choices next time you load the preferences page.