diff --git a/src/front-end/js/book.js b/src/front-end/js/book.js
index e188f9be..46bbacf3 100644
--- a/src/front-end/js/book.js
+++ b/src/front-end/js/book.js
@@ -540,6 +540,10 @@ aria-label="Show hidden lines"></button>';
         /* To allow the sidebar expansion animation, we first need to put back the display. */
         if (!sidebarCheckbox.checked) {
             sidebar.style.display = '';
+            // Workaround for Safari skipping the animation when changing
+            // `display` and a transform in the same event loop. This forces a
+            // reflow after updating the display.
+            sidebar.offsetHeight;
         }
     });