diff --git a/frontend/src/Datarekisteri/Frontend/Types.hs b/frontend/src/Datarekisteri/Frontend/Types.hs
index 129d80f..20e7a2a 100644
--- a/frontend/src/Datarekisteri/Frontend/Types.hs
+++ b/frontend/src/Datarekisteri/Frontend/Types.hs
@@ -287,6 +287,9 @@ instance Yesod DataIdClient where
                 input[type="submit"].reject-button:hover {
                   background-color: #aa3968;
                 }
+                input:invalid {
+                  border-color: #8a003a;
+                }
                 nav {
                   display: block;
                   position: fixed;