Fix sticky footer to work on index page (#674)

* fixing sticky footer not being sticky

* remove unneeded flex rules

* Revert "remove unneeded flex rules"

This reverts commit 9b8d180.

* adding flex-grow to first-child

* adding min-height in 'vh' to .navPusher for it to work on IE11

lib/static/css/main.css

@@ -1852,12 +1852,17 @@ footer .social {
     display: flex;
     flex-direction: column;
     padding-top: 50px;
+    min-height: calc(100vh - 50px);
   }
   .docMainWrapper {
-    flex-grow: 1;
     width: 100%;
     box-sizing: border-box;
   }
+
+  /* those make the footer sticky and work even in IE 11 */
+  .navPusher > :first-child {
+    flex-grow: 1;
+  }
   footer.nav-footer {
     flex-shrink: 0;
   }