CSS Nice Radio Buttons - gecko-8/devwiki GitHub Wiki

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Creates a nice animation between selected states.

input[type="radio"] {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;

  border-radius: 50%;
  width: 24px;
  height: 24px;

  border: 2px solid #392c85;
  transition: 0.2s all linear;
  margin-right: 5px;

  position: relative;
  top: 4px;
}

input[type="radio"]:checked {
  border: 6px solid #392c85;
  outline: unset !important /* I added this one for Edge (chromium) support */
}

Source With Demo