1/* Hide the default checkbox */
2.container input {
3  position: absolute;
4  opacity: 0;
5  cursor: pointer;
6  height: 0;
7  width: 0;
8}
9
10.container {
11  display: block;
12  position: relative;
13  cursor: pointer;
14  font-size: 20px;
15  user-select: none;
16}
17
18/* Create a custom checkbox */
19.checkmark {
20  position: relative;
21  top: 0;
22  left: 0;
23  height: 1.3em;
24  width: 1.3em;
25  background-color: #ccc;
26  border-radius: 100%;
27  background: #e8e8e8;
28  box-shadow: 3px 3px 5px #c5c5c5,
29              -3px -3px 5px #ffffff;
30  transition-duration: 0.5s;
31}
32
33.container input:checked ~ .checkmark {
34  box-shadow: inset 3px 3px 5px #c5c5c5,
35              inset -3px -3px 5px #ffffff;
36}
37
38.checkmark:after {
39  content: "";
40  position: absolute;
41  opacity: 0;
42}
43
44.container input:checked ~ .checkmark:after {
45  opacity: 1;
46}
47
48.container .checkmark:after {
49  left: 0.45em;
50  top: 0.25em;
51  width: 0.25em;
52  height: 0.5em;
53  border: solid darkgray;
54  border-width: 0 0.15em 0.15em 0;
55  transform: rotate(45deg);
56}