Add Troubleshooting doc

docs/Client/troubleshooting.md

@@ -0,0 +1,30 @@
+---
+sidebar_label: Troubleshooting
+---
+
+### If the CSS isn't loading on the Grant Support Access page 
+
+If you have [modified the CSS namespacing](/Client/css-namespacing.md), that is the likley culprit.
+
+Otherwise, this is likely an issue with the `build-sass` script not being passed the same `namespace` flag as the Client is using.
+
+Make sure the `--namespace=` setting in the Composer file:
+
+```json
+"trustedlogin": [
+  "@php vendor/bin/build-sass --namespace=example-namespace"
+],
+```
+
+Matches the `vendor/namespace` setting in the Config settings array:
+
+```php
+$config = [
+    // ...
+	'vendor' => [
+		'namespace' => 'example-namespace',
+    // ...
+];
+```
+
+If those are not the same, the CSS rules will not match the HTML generated and won't be applied.