Consistency in font, color and size matters.
As visitors move through your Web site, they gather clues (unconsciously, perhaps) to the structure of each page. It helps them move to the meat faster. This is part of what makes a user feel comfortable on your site — it’s a good thing and you should protect it.
So a headline in one font, size and color creates an expectation that the next page will have a headline in the same font, size and color. Body text that is suddenly smaller or a lot larger makes a person wonder why it has changed.
Avoid changing body text color for just a few words, as users tend to think colored text is a link (come on, how many of you just clicked on that text or hovered your mouse over it?). Conversely, changing text size for certain short messages can be an effective way to distinguish it from a block of background text.
Notice this small text.
It works for one line, perhaps — but if you do it more than once on a page, the effect is lost. (And you could argue that it’s the white space around that short line that makes it stand out, not the size.) But if you use text size to convey meaning, do it consistently: other pages with similar messages should be treated in the same way, and don’t use the effect for anything else.
Remember the linear concept from a few posts ago? Linear guidelines apply to text as well. Right-justified words may be invisible to some users. I’ll bet some of you, like me, “read” with your cursor, probably about six characters in from the left edge of this text. Am I right? If so, you’ll miss the stuff that’s hanging right. If you’ve got centered text (headlines, perhaps), on a huge monitor they may be just as invisible. In short, for English text displays, I recommend making everything left justified, so there’s a consistent line down which one can skim.
