diff --git a/static/style.css b/static/style.css
index 6d87588..e1223e3 100644
--- a/static/style.css
+++ b/static/style.css
@@ -462,6 +462,21 @@ tr.__table-separator {
     border-bottom: 0.5ex solid black;
 }
 
+/* Side-to-side */
+@media (min-width: 120ex) {
+    body {
+        margin: 0;
+    }
+    .global-table-of-contents {
+        position: fixed;
+        right: 1ex;
+        max-width: calc(100vw - 85ex);
+        top: 1ex;
+        overflow: auto;
+        max-height: 100vh;
+    }
+}
+
 /* Dark mode. */
 @media (prefers-color-scheme: dark) {
     html {