Bug 1503506 - DRM notification displays unnecessary blank spaces before and after Learn More link r=johannh

Differential Revision: https://phabricator.services.mozilla.com/D21594

--HG--
extra : moz-landing-system : lando

toolkit/themes/shared/notification.inc.css

@@ -54,6 +54,10 @@ notification[type="critical"] {
 .messageText > .text-link {
   color: inherit !important;
   text-decoration: underline;
+  margin-top: 0;
+  margin-bottom: 0;
+  margin-inline-start: 0;
+  margin-inline-end: 0;
 }
 
 .messageImage {