diff --git a/web_src/css/form.css b/web_src/css/form.css
index 3a53b6d8f2..bc0aafc893 100644
--- a/web_src/css/form.css
+++ b/web_src/css/form.css
@@ -626,3 +626,7 @@ input:-webkit-autofill:active,
     width: 100% !important;
   }
 }
+
+.captcha-img {
+  width: min(30em, 100%);
+}
\ No newline at end of file