.container {
    position: absolute;
    top: 50%;
    left: 50%;
    background-color: yellow;
    transform: translate(-50%, -50%);
}
.btn {
    position: relative;
    font-family: monospace;
    font-size: 80px;
    text-decoration: none;
    color: black;
    text-transform: uppercase;
    width: 450px;
    height: 150px;
    display: block;
    text-align: center;
    line-height: 150px;
    transition: all .9s;
    overflow: hidden;
}
.btn:hover {
    color: aliceblue;
}
.btn::before,
.btn::after {
    position: absolute;
    content: '';
    width: 100%;
    height: 100%;
    background-color: rgb(231, 165, 50);

    top: 0;
    left: -100%;
    opacity: .5;
    transition: all .8s;
    z-index: -1;
}
.btn::after {
    opacity: 1;
    transition: all .3s;
    background-color: red;
}
.btn:hover::before,
.btn:hover::after {
    left: 0;
}