Move iframe class to top level.

src/default-theme/help.css

@@ -11,24 +11,3 @@
 .jp-Help > iframe {
   border: none;
 }
-
-
-/*
-When drag events occur, `p-mod-override-cursor` is added to the body.
-Because iframes steal all cursor events, the following two rules are necessary
-to suppress pointer events while resize drags are occuring. There may be a
-better solution to this problem.
-*/
-body.p-mod-override-cursor .jp-Help {
-  position: relative;
-}
-
-body.p-mod-override-cursor .jp-Help:before {
-  content: '';
-  position: absolute;
-  top: 0;
-  left: 0;
-  right: 0;
-  bottom: 0;
-  background: transparent;
-}

src/help/plugin.ts

@@ -7,7 +7,7 @@ import {
 
 import {
   IFrame
-} from './iframe';
+} from '../iframe';
 
 
 /**

src/iframe/index.css

@@ -0,0 +1,24 @@
+/*-----------------------------------------------------------------------------
+| Copyright (c) Jupyter Development Team.
+| Distributed under the terms of the Modified BSD License.
+|----------------------------------------------------------------------------*/
+/*
+When drag events occur, `p-mod-override-cursor` is added to the body.
+Because iframes steal all cursor events, the following two rules are necessary
+to suppress pointer events while resize drags are occuring. There may be a
+better solution to this problem.
+*/
+body.p-mod-override-cursor .jp-IFrame {
+  position: relative;
+}
+
+
+body.p-mod-override-cursor .jp-IFrame:before {
+  content: '';
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  background: transparent;
+}

src/index.css

@@ -5,5 +5,6 @@
 |----------------------------------------------------------------------------*/
 @import './dialog/index.css';
 @import './filebrowser/index.css';
+@import './iframe/index.css';
 @import './notebook/completion/index.css'
 @import './terminal/index.css';