diff --git a/postcss.config.cjs b/postcss.config.cjs
index cc02a14e1..51711e182 100644
--- a/postcss.config.cjs
+++ b/postcss.config.cjs
@@ -7,9 +7,22 @@
  * queries (breakpoints follow the window, not the text size), the root size
  * rules themselves, and third-party CSS such as xterm's, which measures in px.
  */
+const pxtorem = require("postcss-pxtorem");
+
+// Production builds minify rounded-full to 3.40282e38px, and pxtorem reads
+// the "38px" tail as its own length, leaving an oval radius behind.
+const EXPONENT_PX = /\d*\.?\d+e[+-]?\d+px\b/gi;
+const keepExponentPx = {
+  postcssPlugin: "termix-keep-exponent-px",
+  Declaration(decl) {
+    decl.value = decl.value.replace(EXPONENT_PX, "calc(infinity * 1px)");
+  },
+};
+
 module.exports = {
-  plugins: {
-    "postcss-pxtorem": {
+  plugins: [
+    keepExponentPx,
+    pxtorem({
       rootValue: 14,
       unitPrecision: 5,
       propList: ["*"],
@@ -18,6 +31,6 @@ module.exports = {
       mediaQuery: false,
       minPixelValue: 2,
       exclude: /node_modules/i,
-    },
-  },
+    }),
+  ],
 };