Client portal custom CSS script not loaded on layout/clean.blade.php template

[brendanlees]

Setup

• Version: v5.8.54-C157
• Environment: ZIP

Interface

• Both

Checklist

• Can you replicate the issue on our v5 demo site https://demo.invoiceninja.com or https://react.invoicing.co/demo? Yes
• Have you searched existing issues? Yes (on forums).
• Have you reported this to Slack/forum before posting? Yes, here.
• Have you inspected the logs in storage/logs/laravel.log for any errors? Yes, nothing related is visible.

Describe the bug

Client portal custom CSS is not loaded on pages using views/portal/ninja2020/layout/clean.blade.php template (payment links, checkout etc).

Steps To Reproduce

Add any sort of custom CSS via client portal area in the admin portal, then create a payment link product and search for the typically inlined styles in the head tags (script does not show).

Expected Behavior

Custom CSS is loaded in the head of document on this view, allowing users to apply consistent styles across all templates.