--- title: "The scope superpower hiding in CSS @function" publication: "Frontend Focus" issue: 746 published_at: "2026-06-17" canonical_url: "https://frontendfoc.us/issues/746" --- Plus Babel 8 lands after eight years, MDN's new MCP server, and view transitions demystified. Together with [![Clerk\](https://res.cloudinary.com/cpress/image/upload/c_fill,g_auto,w_220,h_64/e_make_transparent/co_white,e_outline:5/j3vhv1hnwqeffgkzzlvu.png)](https://go.clerk.com/jKH3MzH) 🚀 **Frontend** Focus #​746 — June 17, 2026 | [Read on the web](https://frontendfoc.us/issues/746) [![\](https://res.cloudinary.com/cpress/image/upload/w_1280,e_sharpen:60,q_auto/uqqo8fwjphal6xmofqme.jpg)](https://developer.mozilla.org/en-US/blog/introducing-mdn-mcp-server/) [Introducing the MDN MCP Server](https://developer.mozilla.org/en-US/blog/introducing-mdn-mcp-server/) — Bring MDN’s docs and browser compatibility data straight into an AI agent or IDE for accurate, up-to-date answers about the web platform, instead of relying on models' stale training data. The MDN Team [![\](https://res.cloudinary.com/cpress/image/upload/c_limit,w_480,h_480,q_auto/copm/809303e1.png)](https://go.clerk.com/jKH3MzH) [clerk deploy: From Dev to Production in One Command](https://go.clerk.com/jKH3MzH) — Run clerk deploy from a linked project and the Clerk CLI walks you through every production requirement: instance clone, DNS records with zone file export, Google and Apple OAuth credentials, and a verification loop for DNS, SSL, and email DNS. Clerk sponsor [The Scope of CSS `@function`](https://master.dev/blog/the-scope-of-css-function/) — A look at the evaluation scope of CSS custom functions: unlike regular custom properties that inherit through the DOM, they resolve variables from wherever they're called, letting library authors hide complex logic behind clean APIs, with some caveats. Jane Ori ⚡️ IN BRIEF - 🟡 [Version 8 of JavaScript compiler Babel landed yesterday](https://babeljs.io/blog/2026/06/16/8.0.0/), some eight years since the last major release. It's now ESM-only. - 🦊 [Firefox 152 was released](https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/152), adding new web platform features including CSS [field-sizing](https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/field-sizing). - ⏱️ TC39 delegate Lucas Casonato has made [a proposal to add built-in localized time formatting](https://github.com/whatwg/html/issues/12591) to HTML. - 🔀 [WASI 0.3 (WebAssembly System Interface) has launched](https://bytecodealliance.org/articles/WASI-0.3), adding native async support to WebAssembly Components. - 💻 _Frontend Masters_ has [rebranded to Master.dev](https://master.dev/blog/today-frontend-masters-becomes-master-dev/) to better reflect the courses they now offer. 📙 Articles, Opinions & Tutorials [![\](https://res.cloudinary.com/cpress/image/upload/w_1280,e_sharpen:60,q_auto/v1781693691/v2xgtkst0odcshspatd0.png)](https://webkit.org/blog/18117/the-golden-rule-of-customizable-select/) [The Golden Rule of Customizable Select](https://webkit.org/blog/18117/the-golden-rule-of-customizable-select/) — When using Safari 27's new customizable `