<button type="button" name="" value="" class="shadow_button3">Button</button>
.shadow_button3{
cursor: pointer;
outline: none;
padding: 1rem 2rem;
box-shadow: 2px 2px 4px gray;
border: 1px solid #ccc;
}
.shadow_button3:active{
transition: 0.2s;
transform: translate3d(0,4px,0);
box-shadow: none;
}