diff --git a/src/main/webapp/plantuml.css b/src/main/webapp/plantuml.css
index 4aa95ed..c9c3646 100644
--- a/src/main/webapp/plantuml.css
+++ b/src/main/webapp/plantuml.css
@@ -28,6 +28,7 @@ h1, p, #content a {
     font-family: monospace;
     font-size: medium;
     width: 100%;
+    resize: vertical;
 }
 
 #content input[type=text] {