/*!
 * Copyright (c) 2018 by Eduardo Sada (https://codepen.io/eduardosada/pen/ObqLQV)
 * Released under the MIT license
 * http://opensource.org/licenses/mit-license.php
 */

html {
  --mouse-x: 0.5;
  --mouse-y: 0.5;
}

.eye {
  display: inline-block;
  overflow: hidden;
  width: 1em;
  height: 1em;
  margin-left: 0.2em;
  margin-right: 0.2em;
  font-size: 30vmin;
  background-color: white;
  border: 0.04em solid black;
  border-radius: 50%;
  position: relative;
  box-shadow: 0.03em 0.14em rgba(0,0,0,0.1);
  box-sizing: content-box;
  will-change: transform;
  animation: blink forwards infinite 10s ease-in-out;
  z-index: 1;
}

.pupil {
  --pupil-size: 0.5em;
  --pupil-padding: calc((1em - var(--pupil-size)) / 2);
  position: absolute;
  width: var(--pupil-size);
  height: var(--pupil-size);
  border-radius: 50%;
  background-color: black;
  border: 0.1em solid #00aeef;
  box-shadow: 0 0 0 0.03em black;
  box-sizing: border-box;
  will-change: transform;
  transition: transform 200ms 300ms ease-in-out;
  transform: translateX(calc(var(--mouse-x) * var(--pupil-padding) + calc(var(--pupil-padding) / 2))) translateY(calc(var(--mouse-y) * var(--pupil-padding) + calc(var(--pupil-padding) / 2)));
}

html:hover .pupil {
  transition: none;
}

@keyframes blink {
  0%, 2%, 60%, 62%, 100% {
    transform: scaleX(1) scaleY(1);
  }
  1%, 61% {
    transform: scaleX(1.3) scaleY(0.1);
  }
}