checkbox.css

/* from https://codepen.io/CreativeJuiz/pen/BiHzp */

/* Base for label styling */
[type="checkbox"]:not(:checked),
[type="checkbox"]:checked {
  position: absolute;
  left: -9999px;
}
[type="checkbox"]:not(:checked) + label,
[type="checkbox"]:checked + label {
  position: relative;
  padding-left: 1.95em;
  cursor: pointer;
}

/* checkbox aspect */
[type="checkbox"]:not(:checked) + label:before,
[type="checkbox"]:checked + label:before {
  content: '';
  position: absolute;
  left: 0; top: 0;
  width: 1.25em; height: 1.25em;
  border: 2px solid #ccc;
  background: #fff;
  border-radius: 4px;
  box-shadow: inset 0 1px 3px rgba(0,0,0,.1);
}
/* checked mark aspect */
[type="checkbox"]:not(:checked) + label:after,
[type="checkbox"]:checked + label:after {
  content: '✔';
  position: absolute;
  top: .1em; left: .3em;
  font-size: 1.3em;
  line-height: 0.8;
  color: #09ad7e;
  transition: all .2s;
}
/* checked mark aspect changes */
[type="checkbox"]:not(:checked) + label:after {
  opacity: 0;
  transform: scale(0);
}
[type="checkbox"]:checked + label:after {
  opacity: 1;
  transform: scale(1);
}
/* disabled checkbox */
[type="checkbox"]:disabled:not(:checked) + label:before,
[type="checkbox"]:disabled:checked + label:before {
  box-shadow: none;
  border-color: #bbb;
  background-color: #ddd;
}
[type="checkbox"]:disabled:checked + label:after {
  color: #999;
}
[type="checkbox"]:disabled + label {
  color: #aaa;
}
/* accessibility */
[type="checkbox"]:checked:focus + label:before,
[type="checkbox"]:not(:checked):focus + label:before {
  border: 2px dotted blue;
}

/* hover style just for information */
label:hover:before {
  border: 2px solid #4778d9!important;
}






/* Useless styles, just for demo design */
/*
body {
  font-family: "Open sans", "Segoe UI", "Segoe WP", Helvetica, Arial, sans-serif;
  color: #777;
}
h1, h2 {
  margin-bottom: .25em;
  font-weight: normal;
  text-align: center;
}
h2 {
  margin: .25em 0 2em;
  color: #aaa;
}
form {
  width: 7em;
  margin: 0 auto;
}
.txtcenter {
  margin-top: 4em;
  font-size: .9em;
  text-align: center;
  color: #aaa;
}
.copy {
 margin-top: 2em; 
}
.copy a {
 text-decoration: none;
 color: #4778d9;
}
*/