Twenty Ten child theme, help about widgets titles with images

Hi everyone, I’m working on a child theme of Twenty Ten and I’d like to have posts titles and widgets titles over a 3D band like in this site: http://www.webfandom.com/page/2/

I got it for the posts titles with this simple code:

<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
			<h2 class="entry-title"><a href="<?php the_permalink(); ?>" title="<?php printf( esc_attr__( 'Permalink to %s', 'twentyten' ), the_title_attribute( 'echo=0' ) ); ?>" rel="bookmark"><?php the_title(); ?></a></h2>
            <div class="triangle"></div>

and these CSS in my stylesheet:

#content .entry-title {
	background: #3399CC;
	padding: 10px;
	padding-left: 31px;
	margin-left: -31px;
	padding-right: 20px;
	margin-right: -20px;
	color: #fff;
	font-size: 21px;
	font-weight: bold;
	line-height: 1.3em;
	margin-bottom: 0;
}
.triangle {
	background: url("images/triangle.png") no-repeat scroll 0;
    float: left;
    height: 18px;
    position: absolute;
    width: 10px;
	margin-left:-31px;
}

Now I can’t do the same with widget titles! More exactly, I can’t add the triangle image under widget title background to obtain 3D effect. I’ve tried many ways but without finding a solution.

Anyone have any ideas to help me? Thanks a lot for any helps!