Index: wp-admin/includes/theme-install.php
===================================================================
--- wp-admin/includes/theme-install.php	(revision 21789)
+++ wp-admin/includes/theme-install.php	(working copy)
@@ -81,7 +81,7 @@
 	<label class="screen-reader-text" for="s"><?php _e('Search by keyword'); ?></label>
 	<?php endif; ?>
 	<input type="search" name="s" id="s" size="30" value="<?php echo esc_attr($term) ?>" autofocus="autofocus" />
-	<?php submit_button( __( 'Search' ), 'button', 'search', false ); ?>
+	<?php submit_button( __( 'Search' ), 'small', 'search', false ); ?>
 </form>
 <?php
 }
Index: wp-admin/themes.php
===================================================================
--- wp-admin/themes.php	(revision 21789)
+++ wp-admin/themes.php	(working copy)
@@ -219,7 +219,7 @@
 <p class="search-box">
 	<label class="screen-reader-text" for="theme-search-input"><?php _e('Search Installed Themes'); ?>:</label>
 	<input type="search" id="theme-search-input" name="s" value="<?php _admin_search_query(); ?>" />
-	<?php submit_button( __( 'Search Installed Themes' ), 'button', false, false, array( 'id' => 'search-submit' ) ); ?>
+	<?php submit_button( __( 'Search Installed Themes' ), 'small', false, false, array( 'id' => 'search-submit' ) ); ?>
 	<a id="filter-click" href="?filter=1"><?php _e( 'Feature Filter' ); ?></a>
 </p>