CSS corner-bottom-right-shape Property

The corner-bottom-right-shape property controls the visual and geometric form of an element’s lower‑right corner - defining whether that corner is squared, rounded, clipped, notched, beveled, or extended into a decorative flourish. Conceptually it acts as a localized modifier to an element’s outline, affecting how the background, border, box‑shadow, and hit testing appear in the bottom‑right quadrant without necessarily changing the element’s overall layout box. Designers use it to give interfaces a distinct personality by changing only one corner rather than the whole radius or outline, allowing more subtle and directional emphasis.

Visually, the property composes with an element’s border and fill: the shape it defines can clip background painting and shadows, and it may alter how borders are drawn where the modified corner meets adjacent edges. It is complementary to broader corner and clipping tools - for example, when used alongside border-radius it provides a targeted override for the lower‑right corner so you can keep other corners uniform while making this one unique. Likewise, it can be used in concert with clip-path or mask-image to create complex visual silhouettes: those primitives affect the whole element, while corner-bottom-right-shape scopes a distinct geometric treatment to just the bottom‑right area.

In practical terms, this property is useful for UI patterns like chat bubbles with a tailored tail or cards with a notch for badges, where only a single corner needs an expressive change. It also supports dynamic styling: animating the corner’s curvature or notch depth can draw attention to an element without changing its position or size. When combining with float-aware layout effects, consider how a corner alteration might interact with text flow and neighboring floats; pairing with shape-outside can create consistent wrapping behavior when an element’s visible outline departs from its rectangular box.

From an accessibility and performance perspective, the property should not remove semantic structure or make interactive targets smaller than their visible affordances: hit testing and focus outlines should remain predictable even if a corner is heavily clipped or extended. Animating complex corner shapes can be GPU‑accelerated in many engines, but excessive use of high‑frequency transitions or very detailed vector shapes may introduce repaint costs, so prefer simple, well‑interpolatable modifications for smooth motion.