Render $...$ / $$...$$ LaTeX in markdown (READMEs, issues, comments) via client-side MathJax, with detection handled server-side by the Hugo passthrough extension plus a custom renderer. Pipeline: - extension/math.go wraps each math span in <span class="math inline| display"> carrying the raw LaTeX with MathJax \( \) / \[ \] delimiters. passthrough handles single-line "$$...$$" blocks and protects markdown inside math; a Pandoc-style guard (no space-padding, no digit after the closing $) keeps currency like "$5 ... $10" from being parsed as math. - layouts/base.html loads MathJax (v4.1.2, tex-svg) on demand, only when a page contains span.math, and typesets just those nodes. Accessibility options are disabled as an initial, conservative implementation. - the sanitizer preserves the math carrier spans. - MathJax is vendored at build time alongside mermaid (flake.nix, the nix static-files package, and the localinfra script). Signed-off-by: oscillatory.net <nick@oscillatory.net>