close_button: use vector icon

plugins/close_button/init.php

@@ -14,15 +14,18 @@ class Close_Button extends Plugin {
 			"fox");
 	}
 
+	function get_css() {
+		return "i.icon-close-article { color : red; }";
+	}
+
 	/**
 	 * @SuppressWarnings(PHPMD.UnusedFormalParameter)
 	 */
 	function hook_article_button($line) {
 		if (!get_pref("COMBINED_DISPLAY_MODE")) {
-			$rv = "<img src=\"plugins/close_button/button.png\"
-				class='tagsPic' style=\"cursor : pointer\"
-				onclick=\"Article.close()\"
-				title='".__('Close article')."'>";
+			$rv = "<i class='material-icons icon-close-article'
+				style='cursor : pointer' onclick='Article.close()'
+				title='".__('Close article')."'>close</i>";
 		}
 
 		return $rv;