diff --git a/site/.vitepress/theme/custom.css b/site/.vitepress/theme/custom.css
index e6baeb8..efa485e 100644
--- a/site/.vitepress/theme/custom.css
+++ b/site/.vitepress/theme/custom.css
@@ -8,3 +8,26 @@
 		"Fira Code", "DejaVu Sans Mono", Menlo, Consolas, monospace;
 	--vp-font-family-mono: var(--vp-font-family-base);
 }
+
+/*
+ * markdown-it-mathjax3 renders each formula as a visible SVG plus a MathML
+ * twin (<mjx-assistive-mml>) for screen readers, and hides the twin with CSS
+ * scoped to a per-container `#mjx-<id>` selector. In the static build the
+ * containers carry no `id`, so that scoped rule matches nothing and the twin
+ * shows up as a second, oversized (theme-monospaced) copy of every formula.
+ * Hide it globally with the standard visually-hidden pattern: it stays in the
+ * DOM for assistive tech but is removed from view and from layout.
+ */
+mjx-assistive-mml {
+	position: absolute !important;
+	top: 0;
+	left: 0;
+	width: 1px !important;
+	height: 1px !important;
+	padding: 0 !important;
+	border: 0 !important;
+	overflow: hidden !important;
+	clip: rect(0 0 0 0) !important;
+	clip-path: inset(50%) !important;
+	white-space: nowrap !important;
+}