1button {
2  padding: 15px 30px;
3  font-size: 18px;
4  outline: none;
5  border: none;
6  border-radius: 10px;
7  transition: 0.5s;
8  background: #1e1e1e;
9  color: greenyellow;
10  box-shadow: 0 0 10px #363636, inset 0 0 10px #363636;
11}
12
13button:hover {
14  animation: a 0.5s 1 linear;
15}
16
17@keyframes a {
18  0% {
19    transform: scale(0.7, 1.3);
20  }
21
22  25% {
23    transform: scale(1.3, 0.7);
24  }
25
26  50% {
27    transform: scale(0.7, 1.3);
28  }
29
30  75% {
31    transform: scale(1.3, 0.7);
32  }
33
34  100% {
35    transform: scale(1, 1);
36  }
37}