Fix sidenotes in commonmark.

_sass/tale/_sidenote.scss

@@ -22,7 +22,13 @@
     display: inline;
   }
 
+  /* kramdown */
   .reversefootnote {
     display: none;
   }
+
+  /* commonmark */
+  .footnote-backref {
+    display: none;
+  }
 }

assets/js/sidenotes.js

@@ -61,9 +61,14 @@
 
     function loadSidenotes(ww, $fnli, fncount, $fn) {
         let minh = 0;
+        // kramdown
         $("sup[role='doc-noteref']").each(function(index, el) {
             minh = showSidenote(el.textContent - 1, $(this), ww, $fnli, minh);
         });
+        // commonmark
+        $("sup[class='footnote-ref']").each(function(index, el) {
+            minh = showSidenote(el.textContent - 1, $(this), ww, $fnli, minh);
+        });
         if (ww > 420) {
             $fn.hide();
         } else {