1button {
2  position: relative;
3  background-color: rgb(230, 34, 77);
4  border-radius: 5px;
5  box-shadow: rgb(121, 18, 55) 0px 4px 0px 0px;
6  padding: 15px;
7  background-repeat: no-repeat;
8  box-sizing: border-box;
9  width: 154px;
10  height: 49px;
11  color: #fff;
12  border: none;
13  font-size: 20px;
14  transition: all .3s ease-in-out;
15  z-index: 1;
16  overflow: hidden;
17}
18
19button::before {
20  content: "";
21  background-color: rgb(248, 50, 93);
22  width: 0;
23  height: 100%;
24  position: absolute;
25  top: 0;
26  left: 0;
27  z-index: -1;
28  transition: width 700ms ease-in-out;
29  display: inline-block;
30}
31
32button:hover::before {
33  width: 100%;
34}