CSS corner-right-shape Property

The corner-right-shape property lets authors carve out or append a visual geometry specifically at an element’s right-hand corner, producing a tailored corner cut, notch, rounded flap, or decorative extension without rewriting the element’s markup. It is designed as a shape-level modifier: rather than shifting the whole box, it alters the silhouette used for painting and hit-testing so the element can look like it has a clipped corner, a triangular ribbon, or a soft beveled edge on its right side. Because it targets only a corner region, it’s useful for localized decoration and functional affordances (badges, speech-tail pointers, folded-corner effects) while keeping the rest of the element’s box intact.

As a visual shaping tool, corner-right-shape composes with other geometry and transform features in predictable ways. For example, you can combine it with border-radius to blend rounded corners and corner-specific cutouts, or use it alongside a general clipping path like clip-path when you need a more complex full-shape mask - the corner-specific shape typically applies first to define the local corner silhouette, and then broader clipping or masks are applied. Applying transforms such as rotations or scales via transform will affect the rendered result of the shaped corner just as they affect the rest of the element, so plan transform origins and stacking contexts carefully if you animate or rotate shaped elements.

In practical authoring, corner-right-shape encourages patterns that keep semantics and interactivity intact: the property alters the painted outline and pointer region but should not, by itself, remove the element from the document flow. Designers often pair a shaped corner with pseudo-elements for layered decoration (so the shape can be decorative while an inner element holds content), or use it for visual signaling on cards and buttons. Because the property can change the hit-test region, it’s important to verify keyboard focus and touch targets remain accessible - if the corner cuts into a previously wide hit area, consider increasing padding or using an alternate focus outline so keyboard and assistive technology users have consistent interaction targets.

From a performance and animation point of view, corner-right-shape is intended to be GPU-friendly when used with simple geometric presets (triangles, arcs, straight notches) but complex procedural shapes may require more expensive repaints. It’s ideal for responsive adjustments - swapping shape presets at different breakpoints gives a different visual emphasis on narrow vs. wide layouts - and for subtle micro-interactions such as hover or focus transitions. When using it for important UI controls, document the behavior for maintainers and provide fallbacks or conservative defaults so the interface remains usable if the visual shape is not supported or is overridden by other masks.