diff --git a/contrib/static/site.css b/contrib/static/site.css
index bebf26c..b58970d 100644
--- a/contrib/static/site.css
+++ b/contrib/static/site.css
@@ -235,3 +235,7 @@ html {
     width: 50%;
     padding: 10px;
 }
+
+#captcha_img {
+    background: grey;
+}
\ No newline at end of file