body {
    background-color: #282828;
}

.btn {
    border: #cfcfcf 0.5vh solid;
    border-radius: 5vh;
    padding: 2vh;
    width: 50vh;
    margin: 3vh auto;
    background-color: #3b3b3b;
    background-image: linear-gradient(to bottom right, #3b3b3b, #303030);
    box-shadow: 1vh 1vh #383838;
}

.btn img {
    height: 40vh;
    display: block;
    margin: auto;
}