CSS Squircle Corner
In the CSS Borders Level 4 draft, squircle is a corner-shape value for a convex superellipse between round and square. It equals superellipse(2), needs a nonzero border radius, and still requires a browser-support check.
Another example
A card has a 24 px radius and uses the draft corner-shape: squircle rule. Supported browsers render it, while @supports keeps a tested border-radius fallback elsewhere and zoom checks clipping and shadows. A rounded-looking screenshot alone cannot prove the squircle value is active.
Main parts
- 01nonzero corner radius
- 02squircle corner shape
- 03support check and fallback
Use it when
Use this term only for the draft CSS squircle curve. Check browser support and provide a tested fallback.
Do not use it when
Do not call every rounded rectangle a squircle. Do not mix the draft keyword with app-icon masks. Test browser support and a fallback shape before shipping.
Name used in code
@supports (corner-shape: squircle) { corner-shape: squircle; } Before you ship
Check content order, shared design values, component consistency, contrast, zoom, and layout changes by screen size. Verify every theme, language, and state. If there is motion, offer an equal reduced-motion experience.
Outcome: Use or define CSS Squircle Corner to make the visual experience clear and easy to use. User context: A card has a 24 px radius and uses the draft corner-shape: squircle rule. Supported browsers render it, while @supports keeps a tested border-radius fallback elsewhere and zoom checks clipping and shadows. A rounded-looking screenshot alone cannot prove the squircle value is active. Design concept to apply: CSS Squircle Corner. Why it fits: Use this term only for the draft CSS squircle curve. Check browser support and provide a tested fallback. Do not use it when: Do not call every rounded rectangle a squircle. Do not mix the draft keyword with app-icon masks. Test browser support and a fallback shape before shipping. Design requirements: Set the content order, shared design values, and reusable components. Define how the layout changes by screen size and state. Keep useful design choices separate from decoration. Inclusion and resilience: Check contrast, zoom, languages, themes, and reduced motion when needed. Do not use color or effects as the only way to show meaning. Acceptance criteria: The design stays clear on phones and desktops, at zoom, in every theme, and in all supported languages. Interactive states stay clear and consistent. Evidence and limits (evidence boundary): A formal document may still be a draft, release candidate, or final version. Check its status and browser or platform support. Unknowns to confirm: Brand limits, amount of content, supported themes and languages, target devices, and design-system rules.
Check this request
Review the current use of CSS Squircle Corner. Definition: In the CSS Borders Level 4 draft, squircle is a corner-shape value for a convex superellipse between round and square. It equals superellipse(2), needs a nonzero border radius, and still requires a browser-support check. Release checks: Check content order, shared design values, component consistency, contrast, zoom, and layout changes by screen size. Verify every theme, language, and state. If there is motion, offer an equal reduced-motion experience. Before changing code, report the evidence you found, gaps, severity, and the smallest safe fix.