The border-radius CSS property rounds the corners of an element's outer border edge. You can set a single radius to make circular corners, or two radii to make elliptical corners.
- <length>
- Denotes the size of the circle radius, or the semi-major and semi-minor axes of the ellipse, using length values. Negative values are invalid.
- <percentage>
- Denotes the size of the circle radius, or the semi-major and semi-minor axes of the ellipse, using percentage values. Percentages for the horizontal axis refer to the width of the box; percentages for the vertical axis refer to the height of the box. Negative values are invalid.
border-radius="4px 3px 6px / 2px 4px"
border-radius="1em/5em"