System Font CSS provides a set of `@font-face` rules that expose the native operating‑system UI font (e.g., San Francisco, Segoe UI, Roboto, Ubuntu) as the CSS generic family `system-ui`. By importing the supplied CSS/SCSS/LESS file, developers can apply consistent system‑font styling—including light, medium, and bold weights with italics—across browsers that support the `system-ui` font family. This lightweight utility is aimed at front‑end developers who want their web pages to inherit the look and feel of the user's OS.