Well, whatever the EM stands for, the rule hides the headings from viewing in Internet Explorer, whereas the rule with EX makes them reappear. Chris
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Anne van Kesteren Sent: Wednesday, June 04, 2008 12:32 PM To: Křištof Želechovski; [EMAIL PROTECTED] Subject: Re: [whatwg] Bad CSS on the multipage version On Wed, 04 Jun 2008 12:25:28 +0200, Křištof Želechovski <[EMAIL PROTECTED]> wrote: > Regarding your page at the URL > <http://www.whatwg.org/specs/web-apps/current-work/multipage/text-level.html > #the-embed>: > The following declaration is bad and wrong: > Is: "margin-top: -2.5em" > Should be: margin-top: -2.5ex" > Wrong: A horizontal unit is applied to a vertical measure > Bad: > Element headings (level 4) are invisible > (obscured underneath the following content). > Please fix ASAP. I don't see that problem. Also, em is just a shorthand for the font-size of the current element (or parent element if you specify it on font-size), it's different from the traditional em unit in that respect. -- Anne van Kesteren <http://annevankesteren.nl/> <http://www.opera.com/>