[Theme: Bueno] Styling featured image

I’ve recently decided to use post thumbnails (featured images) in order to use the “Fix Facebook Like” widget.

So far, I’ve done this:

In Functions.php

// Thumbnails
if ( function_exists( 'add_theme_support' ) )
{ add_theme_support( 'post-thumbnails' );
set_post_thumbnail_size( 490, 350 );
add_image_size( 'single-post-thumbnail', 490, 350 ); }

In single.php, I’ve added this code

<?php the_post_thumbnail( 'single-post-thumbnail' ); ?>

So far, so good. Featured images show up in each entry as well as the main page.

However, I cannot figure out where to change the style of my featured images to the same as my images…

This is my style.css:

/* 3.2 Images */
.entry img { border: 2px solid #330066; }
img.wp-smiley  { padding: 0 !important; border: none !important; margin: 0 !important; }

.entry img, .wp-caption { margin-bottom: 15px; max-width:490px; height: auto; }
.fullwidth .entry img, .fullwidth .wp-caption { max-width:100%; }

.entry .alignleft  { float: left; margin: 10px 15px 10px 0; border: 2px solid #330066; }
.entry .alignright  { float: right; margin: 10px 0 10px 15px; border: 2px solid #330066; }
.entry .aligncenter  { display: block; text-align: center; margin: 10px auto; border: 2px solid #330066; }

.entry .wp-caption { padding: 1px; text-align:center; background:#F8F8F4; border: solid 1px #e6e6e6; }
.entry .wp-caption img{ margin:0; padding:4px 0; background:none; border:0; }
.entry .wp-caption-text { margin:0; padding:0; font-size:11px; text-align:center; }

Website: http://beatricebp.com
Theme: Bueno
Started off on WordPress.com, used the guided transfer to WordPress.org and then played around in the CSS and PHP a bit.