diff --git a/src/renderer/renderScene.ts b/src/renderer/renderScene.ts
index 07c5649c..85e9eab1 100644
--- a/src/renderer/renderScene.ts
+++ b/src/renderer/renderScene.ts
@@ -56,6 +56,7 @@ import {
   getLinkHandleFromCoords,
 } from "../element/Hyperlink";
 import { isLinearElement } from "../element/typeChecks";
+import "./roundRect.polyfill";
 
 export const DEFAULT_SPACING = 2;
 
diff --git a/src/renderer/roundRect.polyfill.ts b/src/renderer/roundRect.polyfill.ts
new file mode 100644
index 00000000..10946a46
--- /dev/null
+++ b/src/renderer/roundRect.polyfill.ts
@@ -0,0 +1,356 @@
+// @ts-nocheck
+
+// source: https://github.com/Kaiido/roundRect/
+// rewritten to remove globalThis and Nullish coalescing assignment operator
+
+export {};
+
+/*
+ *  Implements the .roundRect() method of the CanvasPath mixin
+ *  as introduced by https://github.com/whatwg/html/pull/6765
+ */
+(() => {
+  Path2D.prototype.roundRect ??= roundRect;
+  if (
+    typeof window !== "undefined" &&
+    window.CanvasRenderingContext2D &&
+    !window.CanvasRenderingContext2D.prototype.roundRect
+  ) {
+    window.CanvasRenderingContext2D.prototype.roundRect = roundRect;
+  }
+  if (
+    typeof window !== "undefined" &&
+    window.OffscreenCanvasRenderingContext2D &&
+    !window.OffscreenCanvasRenderingContext2D.prototype.roundRect
+  ) {
+    window.OffscreenCanvasRenderingContext2D.prototype.roundRect = roundRect;
+  }
+
+  function roundRect(x, y, w, h, radii) {
+    if (![x, y, w, h].every((input) => Number.isFinite(input))) {
+      return;
+    }
+
+    radii = parseRadiiArgument(radii);
+
+    let upperLeft;
+    let upperRight;
+    let lowerRight;
+    let lowerLeft;
+
+    if (radii.length === 4) {
+      upperLeft = toCornerPoint(radii[0]);
+      upperRight = toCornerPoint(radii[1]);
+      lowerRight = toCornerPoint(radii[2]);
+      lowerLeft = toCornerPoint(radii[3]);
+    } else if (radii.length === 3) {
+      upperLeft = toCornerPoint(radii[0]);
+      upperRight = toCornerPoint(radii[1]);
+      lowerLeft = toCornerPoint(radii[1]);
+      lowerRight = toCornerPoint(radii[2]);
+    } else if (radii.length === 2) {
+      upperLeft = toCornerPoint(radii[0]);
+      lowerRight = toCornerPoint(radii[0]);
+      upperRight = toCornerPoint(radii[1]);
+      lowerLeft = toCornerPoint(radii[1]);
+    } else if (radii.length === 1) {
+      upperLeft = toCornerPoint(radii[0]);
+      upperRight = toCornerPoint(radii[0]);
+      lowerRight = toCornerPoint(radii[0]);
+      lowerLeft = toCornerPoint(radii[0]);
+    } else {
+      throw new RangeError(
+        `${getErrorMessageHeader(this)} ${
+          radii.length
+        } is not a valid size for radii sequence.`,
+      );
+    }
+
+    const corners = [upperLeft, upperRight, lowerRight, lowerLeft];
+    const negativeCorner = corners.find(({ x, y }) => x < 0 || y < 0);
+
+    if (
+      corners.some(({ x, y }) => !Number.isFinite(x) || !Number.isFinite(y))
+    ) {
+      return;
+    }
+
+    if (negativeCorner) {
+      throw new RangeError(
+        `${getErrorMessageHeader(
+          this,
+        )} Radius value ${negativeCorner} is negative.`,
+      );
+    }
+
+    fixOverlappingCorners(corners);
+
+    if (w < 0 && h < 0) {
+      this.moveTo(x - upperLeft.x, y);
+      this.ellipse(
+        x + w + upperRight.x,
+        y - upperRight.y,
+        upperRight.x,
+        upperRight.y,
+        0,
+        -Math.PI * 1.5,
+        -Math.PI,
+      );
+      this.ellipse(
+        x + w + lowerRight.x,
+        y + h + lowerRight.y,
+        lowerRight.x,
+        lowerRight.y,
+        0,
+        -Math.PI,
+        -Math.PI / 2,
+      );
+      this.ellipse(
+        x - lowerLeft.x,
+        y + h + lowerLeft.y,
+        lowerLeft.x,
+        lowerLeft.y,
+        0,
+        -Math.PI / 2,
+        0,
+      );
+      this.ellipse(
+        x - upperLeft.x,
+        y - upperLeft.y,
+        upperLeft.x,
+        upperLeft.y,
+        0,
+        0,
+        -Math.PI / 2,
+      );
+    } else if (w < 0) {
+      this.moveTo(x - upperLeft.x, y);
+      this.ellipse(
+        x + w + upperRight.x,
+        y + upperRight.y,
+        upperRight.x,
+        upperRight.y,
+        0,
+        -Math.PI / 2,
+        -Math.PI,
+        1,
+      );
+      this.ellipse(
+        x + w + lowerRight.x,
+        y + h - lowerRight.y,
+        lowerRight.x,
+        lowerRight.y,
+        0,
+        -Math.PI,
+        -Math.PI * 1.5,
+        1,
+      );
+      this.ellipse(
+        x - lowerLeft.x,
+        y + h - lowerLeft.y,
+        lowerLeft.x,
+        lowerLeft.y,
+        0,
+        Math.PI / 2,
+        0,
+        1,
+      );
+      this.ellipse(
+        x - upperLeft.x,
+        y + upperLeft.y,
+        upperLeft.x,
+        upperLeft.y,
+        0,
+        0,
+        -Math.PI / 2,
+        1,
+      );
+    } else if (h < 0) {
+      this.moveTo(x + upperLeft.x, y);
+      this.ellipse(
+        x + w - upperRight.x,
+        y - upperRight.y,
+        upperRight.x,
+        upperRight.y,
+        0,
+        Math.PI / 2,
+        0,
+        1,
+      );
+      this.ellipse(
+        x + w - lowerRight.x,
+        y + h + lowerRight.y,
+        lowerRight.x,
+        lowerRight.y,
+        0,
+        0,
+        -Math.PI / 2,
+        1,
+      );
+      this.ellipse(
+        x + lowerLeft.x,
+        y + h + lowerLeft.y,
+        lowerLeft.x,
+        lowerLeft.y,
+        0,
+        -Math.PI / 2,
+        -Math.PI,
+        1,
+      );
+      this.ellipse(
+        x + upperLeft.x,
+        y - upperLeft.y,
+        upperLeft.x,
+        upperLeft.y,
+        0,
+        -Math.PI,
+        -Math.PI * 1.5,
+        1,
+      );
+    } else {
+      this.moveTo(x + upperLeft.x, y);
+      this.ellipse(
+        x + w - upperRight.x,
+        y + upperRight.y,
+        upperRight.x,
+        upperRight.y,
+        0,
+        -Math.PI / 2,
+        0,
+      );
+      this.ellipse(
+        x + w - lowerRight.x,
+        y + h - lowerRight.y,
+        lowerRight.x,
+        lowerRight.y,
+        0,
+        0,
+        Math.PI / 2,
+      );
+      this.ellipse(
+        x + lowerLeft.x,
+        y + h - lowerLeft.y,
+        lowerLeft.x,
+        lowerLeft.y,
+        0,
+        Math.PI / 2,
+        Math.PI,
+      );
+      this.ellipse(
+        x + upperLeft.x,
+        y + upperLeft.y,
+        upperLeft.x,
+        upperLeft.y,
+        0,
+        Math.PI,
+        Math.PI * 1.5,
+      );
+    }
+
+    this.closePath();
+    this.moveTo(x, y);
+
+    function toDOMPointInit(value) {
+      const { x, y, z, w } = value;
+      return { x, y, z, w };
+    }
+
+    function parseRadiiArgument(value) {
+      // https://webidl.spec.whatwg.org/#es-union
+      // with 'optional (unrestricted double or DOMPointInit
+      //   or sequence<(unrestricted double or DOMPointInit)>) radii = 0'
+      const type = typeof value;
+
+      if (type === "undefined" || value === null) {
+        return [0];
+      }
+      if (type === "function") {
+        return [NaN];
+      }
+      if (type === "object") {
+        if (typeof value[Symbol.iterator] === "function") {
+          return [...value].map((elem) => {
+            // https://webidl.spec.whatwg.org/#es-union
+            // with '(unrestricted double or DOMPointInit)'
+            const elemType = typeof elem;
+            if (elemType === "undefined" || elem === null) {
+              return 0;
+            }
+            if (elemType === "function") {
+              return NaN;
+            }
+            if (elemType === "object") {
+              return toDOMPointInit(elem);
+            }
+            return toUnrestrictedNumber(elem);
+          });
+        }
+
+        return [toDOMPointInit(value)];
+      }
+
+      return [toUnrestrictedNumber(value)];
+    }
+
+    function toUnrestrictedNumber(value) {
+      return +value;
+    }
+
+    function toCornerPoint(value) {
+      const asNumber = toUnrestrictedNumber(value);
+      if (Number.isFinite(asNumber)) {
+        return {
+          x: asNumber,
+          y: asNumber,
+        };
+      }
+      if (Object(value) === value) {
+        return {
+          x: toUnrestrictedNumber(value.x ?? 0),
+          y: toUnrestrictedNumber(value.y ?? 0),
+        };
+      }
+
+      return {
+        x: NaN,
+        y: NaN,
+      };
+    }
+
+    function fixOverlappingCorners(corners) {
+      const [upperLeft, upperRight, lowerRight, lowerLeft] = corners;
+      const factors = [
+        Math.abs(w) / (upperLeft.x + upperRight.x),
+        Math.abs(h) / (upperRight.y + lowerRight.y),
+        Math.abs(w) / (lowerRight.x + lowerLeft.x),
+        Math.abs(h) / (upperLeft.y + lowerLeft.y),
+      ];
+      const minFactor = Math.min(...factors);
+      if (minFactor <= 1) {
+        for (const radii of corners) {
+          radii.x *= minFactor;
+          radii.y *= minFactor;
+        }
+      }
+    }
+  }
+
+  function getErrorMessageHeader(instance) {
+    return `Failed to execute 'roundRect' on '${getConstructorName(
+      instance,
+    )}':`;
+  }
+
+  function getConstructorName(instance) {
+    if (typeof window === "undefined") {
+      return "UNKNOWN";
+    }
+    return Object(instance) === instance && instance instanceof Path2D
+      ? "Path2D"
+      : instance instanceof window?.CanvasRenderingContext2D
+      ? "CanvasRenderingContext2D"
+      : instance instanceof window?.OffscreenCanvasRenderingContext2D
+      ? "OffscreenCanvasRenderingContext2D"
+      : instance?.constructor.name || instance;
+  }
+})();