increase immersive reader button margin on tutorials (#11259)

Author: srietkerk

theme/tutorial-sidebar.less

@@ -707,7 +707,7 @@
         padding: .5rem 1rem 0.7rem 1rem;
 
         .tutorial-step-content {
-            margin-right: 1.5rem;
+            margin-right: 2.5rem;
         }
 
         .immersive-reader-button {