diff --git a/tests/test_prepare_mdbook.py b/tests/test_prepare_mdbook.py
index ff43ee7..231510b 100644
--- a/tests/test_prepare_mdbook.py
+++ b/tests/test_prepare_mdbook.py
@@ -193,7 +193,7 @@ Reference :cite:`smith2024`.
             self.assertIn("border-radius: 6px;", rewritten)
             self.assertIn("background: #f6f8fa;", rewritten)
             self.assertIn(".content main {", rewritten)
-            self.assertIn("max-width: min(100%, max(80%, var(--content-max-width)));", rewritten)
+            self.assertIn("max-width: min(100%, max(65%, var(--content-max-width)));", rewritten)
             self.assertIn(".openmlsys-frontpage {", rewritten)
             self.assertIn("width: 100%;", rewritten)
             self.assertIn("margin-inline: auto;", rewritten)
diff --git a/tools/prepare_mdbook.py b/tools/prepare_mdbook.py
index bbe5a34..a01f4fa 100644
--- a/tools/prepare_mdbook.py
+++ b/tools/prepare_mdbook.py
@@ -102,7 +102,7 @@ FRONTPAGE_LAYOUT_CSS = """
   margin-inline: auto;
 }
 .content main {
-  max-width: min(100%, max(80%, var(--content-max-width)));
+  max-width: min(100%, max(65%, var(--content-max-width)));
 }
 @media (max-width: 1000px) {
   .openmlsys-frontpage .mdl-cell,