css: Style outline for any focusable element the same

A recent chrome version changed the focus style again.
Without this some form elements and other focusable
elements get a black outline.

public/css/icinga/base.less

@@ -109,9 +109,7 @@ a {
   }
 }
 
-a:focus,
-button:focus,
-input[type="checkbox"]:focus {
+:focus {
   outline: 3px solid fade(@icinga-blue, 50%);
   outline-offset: 1px;
 }

public/css/icinga/layout.less

@@ -161,7 +161,8 @@
 }
 
 .container,
-.error-message {
+.error-message,
+.modal-window {
   // Don't outline containers and error messages when focused because they receive focus for accessibility only
   // programmatically
   outline: none;

public/css/icinga/login.less

@@ -103,11 +103,6 @@
     }
   }
 
-  input:focus,
-  input[type="submit"]:focus {
-    outline: 3px solid fade(@icinga-blue, 50%);
-  }
-
   .form-controls {
     margin-bottom: 2em;
     margin-top: 2em;