Colour the login page and the dashboard your clients live in, then paste one block of CSS into Agency Settings.
Paste the generated CSS into Settings → Company → Custom CSS
— one block covers both surfaces.
We’ll email you a link to this setup, so you can come back and change it later.
Paste whatever is in Custom CSS right now. Everything you paste is kept — including anything Sidebar Surgeon wrote — and only the Platform Skin block is replaced.