.container {
    position: relative;
    overflow: hidden;
    height: 100vh;
}
.btn {
    z-index: 1;
    appearance: none;
    background-color: darkblue;
    color: white;
    padding: 15px 30px;

    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate3d(-50%, -50%, 0);
}
.kernel {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
    pointer-events: none;
    width: 72px;
    height: 72px;
    background-size: cover;
    background-image: url("kernels-1.png");
    opacity: 0;
}

.kernel-0 {
    background-position: -0px -0px;
}
  
.kernel-1 {
    background-position: -72px -0px;
}

.kernel-2 {
    background-position: -144px -0px;
}

.kernel-3 {
    background-position: -216px -0px;
}

.kernel-4 {
    background-position: -288px -0px;
}

.kernel-5 {
    background-position: -360px -0px;
}

.kernel-6 {
    background-position: -432px -0px;
}

.kernel-7 {
    background-position: -504px -0px;
}

.kernel-8 {
    background-position: -576px -0px;
}
.kernel-9 {
    background-position: -648px -0px;
}