CODE EXAMPLE FOR HTML

slide css

//slide down 
.btn:checked ~ .box {
    clip-path: polygon(0 0, 100% 0, 100% 100%, 0% 100%);
}
.box {
    width: 350px;
    margin-top: 2em;
    position: absolute;
    overflow: hidden;
    border: 1px solid rgba(0, 0, 0, 0.137);
    transition: all 0.4s;
    clip-path: polygon(0 0, 100% 0, 100% 0, 0 0);
    box-shadow: 0px 2rem 10px black;
}