[solved]Widths in IE, Opera and FF

[McCain]

I'm helping a friend with his webpage.
As usual it's the differences in different browsers that's the hardest part about it.
This is what it looks like:

The way it looks in IE/Opera is the way I want it. How do I make it look like that in FF as well?

<div class="s_text">
	<div class="bigPicture">
		<img src="art/room_m.jpg" width="320" height="240" alt="Click this image to get a bigger one">
	</div>
	<div class="infoText">
		<p>This image is really nice</p>
	</div>
	<div class="imgnav">
		<a href="JavaScript:slideshowBack()"><img src="site_images/button_arrow_left.jpg" alt="Previous image" class="arrow" /></a>		
		<div class="navthumbs">
			<img src="art/room_s.bmp" width="50" height="38" 
			/><img src="art/ocean_s.jpg" width="50" height="38" 
			/><img src="art/earth_s.jpg" width="50" height="38" 
			/><img src="art/chair_s.jpg" width="50" height="38" 
			/><img src="art/car_s.jpg" width="50" height="38" 
			/><img src="art/boxx_s.jpg" width="50" height="38" />
		</div>
		<a href="JavaScript:slideshowUp()"><img src="site_images/button_arrow_right.jpg" alt="Next image" class="arrow" /></a>
	</div>
</div>

img {
	border: 0;
	padding: 0;
	margin: 0;
}

img.arrow {
	float: left;
	margin-top: 6px;
}

div.bigPicture {
	font-size: 0;
}

div.bigPicture, div.infoText {
	position: relative;
	left: 50%;
	width: 335px;
	border: 3px solid blue;
	padding: 4px;
	margin: 10px 0 10px -168px;
}

div.imgnav {
	position: relative;
	left: 50%;
	margin: 0 0 10px -199px;
	width: 398px;	
	padding: 0;
	font-size: 0;
}

.imgnav img {
	margin-right: 4px;
}

div.navthumbs {
	float: left;
	border: 3px solid blue;
	padding: 4px 0 4px 4px;
	width: 334px;
	height: 38px;
	margin: 0;
}