Refreshed identity across dashboard and marketing

New LastPriceLogo squircle, refreshed color tokens, and a single shared wordmark component so the dashboard, marketing site, and auth flows finally look like one product.

Visual cleanup pass across every surface. The squircle is the canonical mark; the wordmark component is shared between the auth sidebar and the mobile header so they cannot drift again.

New LastPriceLogo squircle on every auth page

Emerald `L$` mark promoted to the favicon and dashboard accent

Sign in and sign up pages match the dashboard color scheme

Copy passes across the dashboard caught lingering references to the prior brand and unified everything under Last Price

Color tokens consolidated under the Tailwind v4 `@theme inline` block so theming is one file, not scattered overrides