Make the doorhanger narrower in FF

proxy/webext/popup.css

 body {
-	margin: 1em;
+	margin: 10px;
 	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
+	width: 300px;
 }
 
 #active {
-	padding: 2em;
+	padding: 20px;
 	text-align: center;
-	min-width: 128px;
 }
 
 .learn {
-	padding-top: 1em;
+	padding-top: 10px;
 	border-top: 1px solid grey;
 }