diff --git a/website/src/themes/underscore.md.css b/website/src/themes/underscore.md.css
index e8c867a..837d4ca 100644
--- a/website/src/themes/underscore.md.css
+++ b/website/src/themes/underscore.md.css
@@ -37,7 +37,7 @@ h3 {
   line-height: 1.2;
   font-family: -apple-system-font, BlinkMacSystemFont, 'Helvetica Neue', 'PingFang SC', 'Hiragino Sans GB',
     'Microsoft YaHei UI', 'Microsoft YaHei', Arial, sans-serif;
-  font-size: 1.1em;
+  font-size: 14px;
   font-weight: bold;
   margin: 2em 8px 0.75em 0;
   padding-left: 8px;