1.container input {
2  position: absolute;
3  opacity: 0;
4  cursor: pointer;
5  height: 0;
6  width: 0;
7}
8
9.container {
10  position: relative;
11  cursor: pointer;
12  font-size: 17px;
13  width: 2em;
14  height: 2em;
15  border-radius: 50%;
16  user-select: none;
17  border: 5px solid white;
18}
19
20.checkmark {
21  position: absolute;
22  top: 0;
23  left: 0;
24  width: 100%;
25  height: 100%;
26}
27
28.checkmark:after {
29  content: '';
30  position: absolute;
31  top: 25%;
32  left: 25%;
33  background-color: white;
34  width: 50%;
35  height: 50%;
36  border-radius: 50%;
37  transform: scale(0);
38  transition: 100ms ease;
39}
40
41.container input:checked ~ .checkmark:after {
42  transform: scale(1);
43}