[scratchpad] Merge upstream changes into master

Author: jcb91

src/jupyter_contrib_nbextensions/nbextensions/scratchpad/scratchpad.css

@@ -16,7 +16,7 @@
 
 .scratchpad-btn {
   float: right;
-  padding-right: 24px;
+  margin-right: 24px;
   opacity: 0.2;
   font-size: 24px;
   z-index: 106;