What decides this image margin?

[feytus]

I'm designing a webpage now, and using Firebug I'm trying to figure out what decides the image margin on an image I am using on this page;

http://www.kristinemarie.org/?page_id=25

The reason for this, is that I want the margin to be bigger, but I can't for the life of me figure out which parametre to change. Here's the piece of code Firebug points me to;

<a class="shutterset_singlepic11" title="" href="http://www.kristinemarie.org/wp-content/gallery/profilbilder/01_lysere.jpg">
<img class="ngg-singlepic ngg-right" title="Kristine Marie" alt="Kristine Marie" src="http://www.kristinemarie.org/wp-content/gallery/cache/11__320x240_01_lysere.jpg">
</a>

So I'm thinking it's either ngg-singlepic or ngg-right, which I have both tried to change the margin parametres on, but nothing changes, the margin is still the same, no matter what I set it to. Here's the CSS;

.ngg-singlepic {
	display:block;
	border:1px solid #000000; 
	
}

.ngg-left {
	float: left;
	margin-right:10px;
}

.ngg-right {
	float: right;
        margin-left:10px;

Anyone got any idea on what prevents me from making this image margin any bigger? All tips would be greatly appreciated!

[Apostropartheid]

This rule:

.art-article img, img.art-article {
border: solid 1px black;
margin: 1em;
}

Firebug should tell you this.

[feytus]

This rule:

.art-article img, img.art-article {
border: solid 1px black;
margin: 1em;
}

Firebug should tell you this.

Thanks a lot! I could not find that with Firebug (then again, I probably don't know how to use it properly).