There is one little problem with background images.
In IE8 on x64 there is a transparent 1px “padding” between border and top of the background image.
Sample screenshot here


CSS used:

body{background-color:#ccc}
.box
{
margin:10% auto;
padding:30px 50px;
width:60%;
border:1px solid #98a;
background-image:url('opbkg2.gif');
background-repeat:repeat-x;
text-align:center;
-moz-border-radius:9px;
-webkit-border-radius:9px;
-khtml-border-radius:9px;
border-radius:9px;
behavior:url('pie.htc');
}

‘opbkg2′ is a single-pixel vertical line…

update: this ONLY happens if background-repeat:repeat-x is set.
if that line is commented, background properly begins at top border, without that one-pixel transparent line.

Thanks for reporting this. I believe this is another manifestation of the background image clipping issue: viewtopic.php?f=3&t=24

Update:
If background-color is set, "transparent" line gets filled with background-color.
IE6 is unaffected, IE7 is unaffected. So far I had not tested on IE8 on 32-bit systems, but IE8 on x64 is affected.

Additional tests results:
Background as a whole is not moved.
Instead, only one line gets "cut" and then "pasted" at "other side" of the background image.

More info.
If background is set to no-repeat only top and left lines get cut.

If background is set to repeat-x, only top line gets cut. Left line is not affected.

If background is set to repeat-y, only left line gets cut. Top line is not affected.

background used (note dotted white-black border all around background image):


test case results:


Hope this can be of use.

That does help, thank you!