How to reduce the signature border's width?

[Emeralda]

I could somehow understand the making new class thing, but how do you remove it from the current sig and add a new border like that?

				{vb:raw template_hook.postbit_signature_start}
				<vb:if condition="$post['isfirstshown']">
					{vb:raw ad_location.ad_showthread_firstpost_sig}
				</vb:if>
				<vb:if condition="$post['signature']">
					<blockquote class="signature restore"><div class="signaturecontainer">{vb:raw post.signature}</div></blockquote>
				</vb:if>
				{vb:raw template_hook.postbit_signature_end}

Is something about it there?