diff --git a/prototype/src/main/resources/static/css/ecom.css b/prototype/src/main/resources/static/css/ecom.css
index fa56af0..91f4b89 100644
--- a/prototype/src/main/resources/static/css/ecom.css
+++ b/prototype/src/main/resources/static/css/ecom.css
@@ -38,6 +38,8 @@
 
    --c-black: var(--root-c-black);
    --c-black-highlight: var(--root-c-black-highlight);
+
+   --c-error: #c0392b;
 }
 
 .primary {
@@ -218,6 +220,12 @@ input[type="password"] {
    /* box-shadow: var(--s-0-secondary); */
 }
 
+input[type="text"]:invalid,
+input[type="password"]:invalid {
+   background-color: var(--c-error);
+   color: var(--c-base);
+}
+
 input[type="text"]::placeholder,
 input[type="password"]::placeholder  {
   color: var(--c-primary-highlight);