- From: Michael Cooper <mcooper@cast.org>
- Date: Wed, 3 May 2000 15:04:43 -0400
- To: "Leonard R. Kasday" <kasday@acm.org>, <w3c-wai-gl@w3.org>
- Cc: <w3c-wai-er-ig@w3.org>
The issue there is that the second paragraph on the page is absolutely positioned with respect to the _page_, not to the paragraph above it. When a font size change or window resize cause the first paragraph to have more lines than you planned on, the format breaks. It's not the relative units at issue though, it's what they're relative to. That's a subtle and hard-to-explain distinction that I also have run afoul of, but there are ways to make it work. In the case of this example, you can use _relative_ positioning and used em or ex units, and it would stay in the same relative position regardless of font or window changes. For instance, try replacing the existing style attribute with the following one: style="position:relative; left:0em; top:2ex;". Michael Cooper mcooper@cast.org -----Original Message----- From: w3c-wai-er-ig-request@w3.org [mailto:w3c-wai-er-ig-request@w3.org]On Behalf Of Leonard R. Kasday Sent: Wednesday, May 03, 2000 2:04 PM To: w3c-wai-gl@w3.org Cc: w3c-wai-er-ig@w3.org Subject: Low Vision and CSS (The EM is not enough) To WCAG Copied to ER People with low vision often increase the default font size. One might think this could be accommodated by using em units instead of absolute units, but that doesn't appear to be the case. If you look at http://astro.temple.edu/~kasday/wai/css-em.html using Internet Explorer 5, with medium font size, and a window approximately a screen width, you'll see a paragraph at the top and text below it. The lower text is positioned with respect to the window with ems. However, if you now make the window smaller, you'll see the text in the top paragraph wrap, causing the number of lines to increase and it will eventually overlap the text below it. Similarly, if you make the font bigger using View->font size, you'll again get the overlap. The moral is that, checkpoint 3.4 to use relative units such as the EM is not enough. There needs to be a more general guideline that pages shall read sensibly when default font is made larger. For convenience, I've included the text of the referenced example in this email. Len p.s. Presently, this example works only in MSIE 5, not Opera 3.62 or Netscape 4.7. I think MSIE is doing it right. CSS gurus please check... ========== This shows that text can overlap even when using ems. If you make screen narrower or font larger the text will overlap... at least in Microsoft Internet Explorer 5.0 (Overlap does not occur in Opera 3.62, and Netscape Communicator doesn't show it at all). This sentence starts out below the first one. Len Kasday, kasday@acm.org, Pennsylvania's Initiative on Assistive Technology, a program of the Institute on Disabilities/UAP at Temple University -- Leonard R. Kasday, Ph.D. Institute on Disabilities/UAP, and Department of Electrical Engineering Temple University 423 Ritter Annex, Philadelphia, PA 19122 kasday@acm.org http://astro.temple.edu/~kasday (215) 204-2247 (voice) (800) 750-7428 (TTY)
Received on Wednesday, 3 May 2000 15:12:35 UTC