.btn-3d {
    top: 0;
    left: 0;
    transition: all 0.15s linear 0s;
    position: relative;
    display: inline-block;
    padding: 15px 25px;
    background-color: var(--main-color);
    text-transform: uppercase;
    color: #404040;
    font-family: arial;
    letter-spacing: 1px;
    box-shadow: -6px 6px 0 #404040;
    text-decoration: none;
}

.btn-3d:hover {
    top: 3px;
    left: -3px;
    box-shadow: -3px 3px 0 #404040;
}

.btn-3d:hover::after {
    top: 1px;
    left: -2px;
    width: 4px;
    height: 4px;
}

.btn-3d:hover::before {
    bottom: -2px;
    right: 1px;
    width: 4px;
    height: 4px;
}

.btn-3d::after {
    transition: all 0.15s linear 0s;
    content: "";
    position: absolute;
    top: 2px;
    left: -4px;
    width: 8px;
    height: 8px;
    background-color: #404040;
    transform: rotate(45deg);
    z-index: -1;
}

.btn-3d::before {
    transition: all 0.15s linear 0s;
    content: "";
    position: absolute;
    bottom: -4px;
    right: 2px;
    width: 8px;
    height: 8px;
    background-color: #404040;
    transform: rotate(45deg);
    z-index: -1;
}

a.btn-3d {
    position: relative;
}

a:active.btn-3d {
    top: 6px;
    left: -6px;
    box-shadow: none;
}

a:active.btn-3d:before {
    bottom: 1px;
    right: 1px;
}

a:active.btn-3d:after {
    top: 1px;
    left: 1px;
}