<!doctype html> <style> * { margin: 0; } .outer { position: absolute; overflow: hidden; border-radius: 9999px; width: 300px; height: 300px; } .inner { position: absolute; top: 0px; bottom: 0px; width: 300px; height: 300px; background: mediumspringgreen; } </style><body><div class="outer"><div class="inner"></div>
