ul.color-list-field {
  overflow: auto;
  list-style-type: none;
  padding: 15px 1.5em;
}
ul.color-list-field li {
  float: left;
  position: relative;
  margin: 0 0.75em 0.75em 0;
}
ul.color-list-field li input {
  display: none;
}
ul.color-list-field li input:checked + span {
  -webkit-box-shadow: 0px 0px 2px 2px rgba(0, 0, 0, 0.8);
  -moz-box-shadow: 0px 0px 2px 2px rgba(0, 0, 0, 0.8);
  box-shadow: 0px 0px 2px 2px rgba(0, 0, 0, 0.8);
  border: 3px solid #e6e6e6;
  -webkit-transition: border 500ms;
  -moz-transition: border 500ms;
  -o-transition: border 500ms;
  transition: border 500ms;
}
ul.color-list-field li span {
  width: 50px;
  height: 50px;
  display: block;
  cursor: pointer;
  border: 10px solid #e6e6e6;
  border-radius: 50px;
}
ul.color-list-field {
  overflow: auto;
  list-style-type: none;
  padding: 15px 1.5em;
}
ul.color-list-field li {
  float: left;
  position: relative;
  margin: 0 0.75em 0.75em 0;
}
ul.color-list-field li input {
  display: none;
}
ul.color-list-field li input:checked + span {
  border: 5px solid rgba(0, 0, 0, 0.3);
  -webkit-transition: border 500ms;
  -moz-transition: border 500ms;
  -o-transition: border 500ms;
  transition: border 500ms;
}
ul.color-list-field li span {
  width: 50px;
  height: 50px;
  display: block;
  cursor: pointer;
  border: 12px solid #e6e6e6;
  border-radius: 50px;
}

Update box-shadow to transparent stroke
Update box-shadow to transparent stroke