Reader’s advice: iframe bug in Firefox

Firefox iframe bug

In Firefox there’re those annoying black 1px thin horizontal lines inside iframe. I haven’t found anything useful so far, even though the bug has been mentioned here and there.

So, the question is – what’s your experience with this nasty thingy? To make this even more interesting, the one who comes with the bulletproof solution will receive a copy of CSS Mastery, Dom Scripting or ppk on JavaScript.


This error occures in Firefox, both Win and Mac.

Update 2

The workaround for the above is to set rule position: absolute to an iframe. No coordinates should be specified (left or top), and the parent element should not be set to position: relative, as this throws the iframe back to square one.

Ed’s note: The bug has nothing to do with the ‘rounding error’.

Update 3

You’ll have to register at to see the working example.

Marko Dugonjić is a designer specialized in user experience design, web typography and web standards. He runs a nanoscale user interface studio Creative Nights and organizes FFWD.PRO, a micro-conference and workshops for web professionals.

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