Uncle Pirate said:
Personally, I pretty much leave text sizes alone. I very rarely specify
a font either; I figure the default is good enough. I sometimes set hx
sizes and usually use large, x-large, or xx-large; are those fixed
sizes? Should I be using 100+% instead?
They are flexible sizes and will increase/decrease with the user's
chosen default, etc. so there's no accessibility/usability reason not
to use them.
However, there are two other reasons that may lead you to not use the
keywords.
1. IE5 (and IE6 in quirks mode) treats small as equivalent to the
browser default, so large is two 'steps' larger than the default
rather the one step larger that it is in other browsers. It's
relatively easy to give different styles to IE5 and with larger sizes
it's not critical as you don't run the same risks of illegibility that
you do when using the small, x-small, xx-small keywords.
2. You don't have any fine control. You know that x-large will be
displayed larger than large and so on but you don't know exactly how
big any given browser will display it. (And if you want to use the
full range of H1 - H6 then only having three, or four in the case of
IE5 ;-/ sizes above the body copy size may be a problem. But, of
course, there are other ways to distinguish headings other than font
size.)
If neither of those issues are a problem for you then by all means
carry on using the keywords.
Steve