Requests number in the customer portal user dropdown cannot be seen if banner background colour is close to white

Issue Summary

Requests number in the user dropdown cannot be seen if banner background colour is closed to white

Steps to Reproduce

1. Go to a project with customer portal enabled. Create some issues so the number of requests is larger than 0.
2. Go to project settings, then portal settings.
3. Click `View and customize the look and feel of your Help Center.`
4. Change Banner background to `#ffffff`.
5. Click the user profile dropdown, the `My requests` with number text is now white and matched the background white which makes the number unreadable.
6. Change Banner background to `#239227`.
7. Click the user profile dropdown, the "number of requests" text is now readable. (see screenshots attached).

Expected Results

Whatever banner background (light or dark) that the user chose, it should use the contrast colour to show the number of notifications in readable colour.

Actual Results

When the banner background is white or closed to white, the number of requests is unreadable because its colour is matching the background.

Workaround

Customers can change the banner background to some colour that is not closed to white which will work as a workaround.