1.btn-wrapper {
2  width: 120px;
3  height: 50px;
4  position: relative;
5  z-index: 1;
6  background: linear-gradient(270deg, #96f061, #a259d3, #1d9de0, #e790b0);
7  box-shadow: 2px 2px 10px rgba(255, 255, 255, 0.363);
8  background-size: 800% 800%;
9  animation: animateBorder 9s ease infinite;
10}
11
12.btn {
13  width: 95%;
14  height: 90%;
15  position: absolute;
16  padding: 5px;
17  border: none;
18  top: 50%;
19  left: 50%;
20  transform: translate(-50%, -50%);
21  background-color: #212121;
22  z-index: 2;
23  text-transform: uppercase;
24  letter-spacing: 4.5px;
25  color: white;
26  font-weight: bold;
27}
28
29@keyframes animateBorder {
30  0% {
31    background-position: 0% 50%
32  }
33
34  50% {
35    background-position: 100% 50%
36  }
37
38  100% {
39    background-position: 0% 50%
40  }
41}