.back-to-parent-btn:before {
    content: "";
    background-image: url(https://bios.lv/embed.svg);
    width: 1rem;
    height: 1rem;
    background-size: 1rem;
    position: absolute;
    left: 0.65rem;
    top: 0.65rem;
}
.back-to-parent-btn {
    padding-left: 2rem;
    background-color: blue;
    border-color: lime;
    color: white;
}
.back-to-parent-btn:hover {
    background-color: purple;
    border-color: transparent;
    color: green;
}