Okay, I would either a. put the divs around each of the error boxes, OR b, give the "img" tag itself a ID or a class which you could then change.
Here might be an example, very loosely of course.
Code:
<img class="usererror" src="images/error.png" border="0" width="16" height="16" />
"usernameinput"
<img class="passerror" src="images/error.png" border="0" width="16" height="16" />
"passworderror"
Code:
img.usererror {
height:16px;
height:16px;
float:left;
}
img.passerror {
height:16px;
height:16px;
float:left;
}
This is VERY rough, I don't know the full details of how your site is coded or anything, so you'll have to probably edit things so they work for you.