border-radius rounds the outer corners of an element's border box. You can set one value to round all four corners equally, or up to four values to control the top-left, top-right, bottom-right, and bottom-left corners individually.
Set border-radius to 50% on an element that has equal width and height. If the width and height differ, 50% produces an ellipse instead of a circle.
Yes. Pixel values create a fixed corner radius, while percentage values are relative to the element's dimensions and scale as the box resizes. This generator outputs pixel values from its sliders.
Yes. border-radius is a stable CSS3 property supported by all modern browsers, including Chrome, Firefox, Safari, and Edge, with no vendor prefixes needed for current versions.