Index: wp-content/themes/twentyeleven/style.css
===================================================================
--- wp-content/themes/twentyeleven/style.css	(revision 18313)
+++ wp-content/themes/twentyeleven/style.css	(working copy)
@@ -1946,9 +1946,26 @@
 	top: 2.2em;
 }
 a.comment-reply-link {
+	background: #eee;
+	-moz-border-radius: 3px;
+	border-radius: 3px;
+	color: #666;
+	display: inline-block;
 	font-size: 12px;
-	font-weight: bold;
+	padding: 0px 8px;
+	text-decoration: none;
 }
+a.comment-reply-link:hover,
+a.comment-reply-link:focus,
+a.comment-reply-link:active {
+	background: #888;
+	color: #fff;
+}
+a.comment-reply-link > span {
+	display: inline-block;
+	position: relative;
+	top: -1px;
+}
 
 /* Post author highlighting */
 .commentlist > li.bypostauthor {
Index: wp-content/themes/twentyeleven/functions.php
===================================================================
--- wp-content/themes/twentyeleven/functions.php	(revision 18313)
+++ wp-content/themes/twentyeleven/functions.php	(working copy)
@@ -538,7 +538,7 @@
 			<div class="comment-content"><?php comment_text(); ?></div>
 
 			<div class="reply">
-				<?php comment_reply_link( array_merge( $args, array( 'reply_text' => __( 'Reply &darr;', 'twentyeleven' ), 'depth' => $depth, 'max_depth' => $args['max_depth'] ) ) ); ?>
+				<?php comment_reply_link( array_merge( $args, array( 'reply_text' => __( 'Reply <span>&darr;</span>', 'twentyeleven' ), 'depth' => $depth, 'max_depth' => $args['max_depth'] ) ) ); ?>
 			</div><!-- .reply -->
 		</article><!-- #comment-## -->
 
Index: wp-content/themes/twentyeleven/colors/dark.css
===================================================================
--- wp-content/themes/twentyeleven/colors/dark.css	(revision 18313)
+++ wp-content/themes/twentyeleven/colors/dark.css	(working copy)
@@ -455,6 +455,22 @@
 .comment-meta {
 	color: #999;
 }
+a.comment-reply-link {
+	background: #242424;
+	color: #bbb;
+}
+li.bypostauthor a.comment-reply-link {
+	background: #111;
+}
+a.comment-reply-link:hover,
+a.comment-reply-link:focus,
+a.comment-reply-link:active,
+li.bypostauthor a.comment-reply-link:hover,
+li.bypostauthor a.comment-reply-link:focus,
+li.bypostauthor a.comment-reply-link:active {
+	background: #999;
+	color: #000;
+}
 .commentlist > li:before {
 	content: url(../images/comment-arrow-dark.png);
 }