web: restore scrollbars and scroll behaviour

Currently pageup/pagedown, etc. keys don't do anything.

I tried a couple of things; including putting refs on various things
and trying to give them focus on componentDidMount(), but the scroll
keys didn't seem to make it in.

This I just found from fiddling around with the inspector.  Resetting
these overflow values gives me a standard "whole-page" scroll bar on
the left hand side, and all the expected keyboard nagivation keys
work.

Honestly, this is maybe more for discussion with someone who
understands patternfly page/panels etc. a bit more; but empirically it
seems to work.

Change-Id: Ib723b125e39f707972a15891ec411f322c335993

web/src/index.css

@@ -370,3 +370,9 @@ details.foldable[open] summary::before {
         );
     }
 }
+
+/* This restores correct scroll bar and scrolling behaviour */
+.pf-c-page__main {
+    overflow-x: visible;
+    overflow-y: visible;
+}