Help IE to outline the focus

public/css/icinga/base.less

@@ -80,15 +80,19 @@ a {
   color: inherit;
   text-decoration: none;
 
-  &:focus {
-    outline-color: @icinga-blue;
-  }
-
   &:hover {
     text-decoration: underline;
   }
 }
 
+a:focus,
+button:focus,
+input[type="checkbox"]:focus {
+  outline-color: @icinga-blue;
+  outline-style: solid; // IE
+  outline-style: auto;
+}
+
 // Default margin for block text
 blockquote, p, pre {
   margin: 0 0 1em 0;