diff --git a/phpBB/styles/prosilver/theme/buttons.css b/phpBB/styles/prosilver/theme/buttons.css
index 4656128ab9..f4671ff58c 100644
--- a/phpBB/styles/prosilver/theme/buttons.css
+++ b/phpBB/styles/prosilver/theme/buttons.css
@@ -32,6 +32,20 @@
 	outline: none;
 }
 
+.button[disabled],
+.button[disabled]:hover,
+.button.disabled,
+.button.disabled:hover {
+	background: #eee;
+	color: #aaa;
+	border-color: #aaa;
+	cursor: default;
+}
+
+.button.hidden {
+	display: none;
+}
+
 .caret {
 	border-left: 1px solid;
 	position: relative;
diff --git a/phpBB/styles/prosilver/theme/colours.css b/phpBB/styles/prosilver/theme/colours.css
index 7bdd5f4b87..ae39635d65 100644
--- a/phpBB/styles/prosilver/theme/colours.css
+++ b/phpBB/styles/prosilver/theme/colours.css
@@ -697,6 +697,15 @@ dd.profile-warnings {
 	color: #d41142;
 }
 
+.button[disabled],
+.button[disabled]:hover,
+.button.disabled,
+.button.disabled:hover {
+	background: #e0e0e0;
+	color: #9e9e9e;
+	border-color: #9e9e9e;
+}
+
 .button .icon,
 .button-secondary,
 .c-button-icon {