Limitations

While Squircle is designed to work seamlessly across all modern browsers, there are a few limitations to keep in mind:

• Squircle uses a custom polyfill, @squircle/paint-polyfill, a heavily improved fork of css-paint-polyfill. This polyfill brings CSS Houdini compatibility to browsers that do not support CSS.paintWorklet natively.

• However, very old browsers, such as Internet Explorer and some early versions of Edge, are not supported. These browsers do not support the necessary underlying APIs to run the polyfill reliably. (Note: Internet Explorer is not officially tested and should be considered unsupported.)

• In browsers without native CSS Houdini support (thus relying on @squircle/paint-polyfill), there may be minor performance overhead. This is because the polyfill actively listens to style changes and dynamically replaces paint operations in the DOM, which can slightly impact performance, especially in large or highly dynamic applications.

In fully CSS Houdini-compatible browsers, Squircle has near-zero performance impact and runs natively without any emulation layer.

Browser Support

Squircle is designed to work seamlessly across all modern browsers:

• ✅: Supported natively
• ☑️: Supported with @squircle/paint-polyfill (see limitations)
• ❌: Not supported