Colour the login page and the dashboard your clients live in, then paste one block of CSS into Agency Settings.
Save these settings so you can update them later — we email you a link back to this exact setup.
Open it to copy your CSS. The code lives on that link, so the setup is always one click away and you can keep editing it later.
Paste whatever is in Custom CSS right now. Everything you paste is kept — including anything Sidebar builder wrote — and only the Platform Skin block is replaced.
Paste the generated CSS into Settings → Company → Custom CSS
— one block covers both surfaces.