KaTeX stylesheet never loads, math renders twice as raw MathML + HTML #4606

Math blocks on the live site render twice: unstyled MathML (num_vectors shows as num with subscript v) followed by the KaTeX HTML output, with no KaTeX fonts.

Example: https://www.elastic.co/docs/deploy-manage/production-guidance/optimize-performance/approximate-knn-search#raw-vector-storage

The source is fine (\text{num\_vectors}). The page is just missing KaTeX's CSS, which is what hides .katex .katex-mathml.

Evidence

• initMath in Assets/main.ts lazy-loads the CSS with import('./katex.css') (added in Assets: Lazy-load KaTeX JS, CSS, and fonts #3660).
• The production bundle (/docs/_static/main-1OEc8Qmr.js) compiles that to C(()=>Promise.resolve({}), __vite__mapDeps([43]), import.meta.url), where dep 43 is ./chunk-katex-BtZVJ23X.css.
• The chunk is served (200, contains the .katex-mathml rule), but the bundle contains no code that inserts a <link rel="stylesheet">, so nothing ever requests it.

Likely cause

Regression from the Parcel to Vite migration (#4383). The dynamic CSS import becomes a no-op unless the preload helper injects the CSS deps, and that helper does not appear in the output.

Possible fixes

• Check build.modulePreload and the Rolldown output, and make sure CSS deps of dynamic imports get injected.
• Or inject the stylesheet explicitly in initMath (new URL('./katex.css', import.meta.url) plus a <link>).
• Or import katex.css eagerly again. It is about 29 KB.

Add a test that renders a math block and asserts that .katex-mathml is not visible, so this does not regress again.