CSS corner-bottom-shape Property

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Description

The corner-bottom-shape property provides a declarative way to control the exact geometry of an element’s lower corners without rewriting the whole outline. Instead of a single uniform radius or a generic clip, it lets a designer define distinct shapes for the bottom-left and bottom-right corners - from soft rounded contours to sharp bevels, notches, chevrons or concave arcs - and have those shapes applied to the element’s painting and hit-testing boundaries. Because it targets only the lower corners, it is ideal for visual patterns where the top of a box remains regular while the bottom needs custom treatment (for example conversational bubbles, cards with notched footers, or decorative callouts).

When used in combination with other box-related rules it composes predictably: the shapes defined by corner-bottom-shape influence how the element’s background and border are painted and how overflow is clipped, much like how background-clip and border-radius affect painting. If you need more complex silhouettes or non-rectangular text flow, it can be used together with clip-path or mask-image - use corner-bottom-shape when you want a concise semantic way to target only the bottom corners and maintain simpler layout boxes, and prefer the other tools for full arbitrary masking or complex polygon clipping.

The property is intended to animate smoothly so it works well in transitions and micro-interactions; pairing changes to corner-bottom-shape with transforms produces polished effects where a card or panel morphs its lower corners while scaling or moving. For such animated uses, you should be mindful of repaints and compositing costs: complex corner geometry may force the browser to re-rasterize the element, so combine with layout-friendly techniques like transform for motion and limit frequent heavy updates.

For robustness and accessibility, treat corner shaping as a decorative enhancement rather than a replacement for semantic cues. Provide sufficient contrast and spacing so interactive targets remain large enough despite visual clipping, and offer fallbacks (for example a plain rectangular presentation) in contexts where the decorative corners might interfere with content legibility or printing. When designing, prefer subtle shapes for dense interfaces and reserve dramatic bottom corner treatments for cases where the shape supports the content’s meaning or visual hierarchy.

Definition

Initial value: see individual properties
Applies to: see individual properties
Inherited: no
Computed value: see individual properties
Animatable: see individual properties
JavaScript syntax: object.style.cornerBottomShape

Syntax

corner-bottom-shape: <corner-shape>{1,2}

Values

The property accepts one or two <corner-shape-value> values. These define the style of the corner shape:

Keyword Values

round - The default value. Creates a standard rounded corner (equivalent to traditional border-radius).
scoop - Creates an inward-facing curve (concave), making the corner look "bitten" out.
bevel - Creates a flat, diagonal cut across the corner (chamfered look).
notch - Creates a rectangular step-like cutout at the corner.
square - Straight angle corner (no rounding)
squircle - Intermediate shape between round and square

Functional Value

superellipse(<number>) - Determines corner curvature using a superellipse curve.
- Larger positive numbers → closer to a square
- Values around 1 → default/round
- Negative values → inverted/concave shapes
- infinity and -infinity are allowed as extremes ([MDN Web Docs][1])

Global CSS Values

inherit
initial
revert
revert-layer
unset

Example

HTML

<div class="wrap">

  <div class="card" style="--corner-bottom-shape: 48px;">

    <h2>Corner bottom shape</h2>

    <p>This card demonstrates a customizable bottom-corner shape using a CSS custom property.</p>

  </div>

</div>

CSS

body {
  margin: 40px;
  background: blue;
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;
  color: #0f172a;
}

.wrap {
  width: 380px;
  margin: 0 auto;
}

/* Card with adjustable bottom-corner shape */
.card {
  position: relative;
  background: linear-gradient(180deg, #ffffff 0%, #fbfbfc 100%);
  padding: 24px;
  border-radius: 30px;
  box-shadow: 0 8px 24px rgba(16, 24, 40, 0.08);
  corner-bottom-shape: scoop;
  overflow: visible; /* allow pseudo-elements to overlap if needed */
}

.card h2 {
  margin: 0 0 8px 0;
  font-size: 18px;
  line-height: 1.1;
}

.card p {
  margin: 0;
  color: #475569;
  font-size: 14px;
}

Result

Editor

Browser Support

The following information will show you the current browser support for the CSS corner-bottom-shape property. Hover over a browser icon to see the version that first introduced support for this CSS property.