CSS for greying out login form

src/skins/vector/css/matrix-react-sdk/structures/login/_Login.scss

@@ -67,6 +67,10 @@ limitations under the License.
     margin-bottom: 14px;
 }
 
+.mx_Login_field_disabled {
+    opacity: 0.3;
+}
+
 .mx_Login_fieldLabel {
     margin-top: -10px;
     margin-left: 8px;
@@ -87,6 +91,10 @@ limitations under the License.
     color: $accent-fg-color;
 }
 
+.mx_Login_submit:disabled {
+    opacity: 0.3;
+}
+
 .mx_Login_label {
     font-size: 13px;
     opacity: 0.8;

src/skins/vector/css/matrix-react-sdk/views/elements/_Dropdown.scss

@@ -18,6 +18,10 @@ limitations under the License.
     position: relative;
 }
 
+.mx_Dropdown_disabled {
+    opacity: 0.3;
+}
+
 .mx_Dropdown_input {
     position: relative;
     border-radius: 3px;