<p>i have code like, sorry i dont have the exact code now. but its valid.</p>

<pre><code>&lt;iframe src="..." borderframe="0" scrolling="no" width=728px" height="90px"&gt;&lt;/iframe&gt;
</code></pre>

<p>the target is a html file that contains code for a banner. 
everything displays well. but when i resize browser or go to maximize. the content is shiftet to the left by 1 pixel. so the banner is displayed missing the first vertical 1px line. and only 727px is visible.</p>

<p>anyone has an idea?</p>

<p>thank you.</p>

I have an idea, but you haven't given us the whole picture, so I might be way off.
I would guess that the iframe is positioned with a percentage or some sort of division calculation like 40% left of parent.  Then at certain browser widths this number doesn divide evenly and gets truncated.  Say it is at 100px in from the left side, and you shrink the parent by 2/3rds so that its positioning would become 66.66 pixels, and the browser cuts this off to 66, giving an apparent error of one pixel left.