.dropbtn {
    color: lightslategray;
    background-color: snow;
    font-size: inherit;
    font-family: inherit;
    border: none;
    height: 30px;
    width: 75px;
    border: 1px slategray solid;
    border-radius: 5px;
    cursor: pointer;
    line-height: 30px;
    text-align: center;
}

.dropdown {
    position: relative;
    display: inline-block;
}

.dropdown-menu {
    display: none;
    position: absolute;
    background-color: #f1f1f1;
    box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
    z-index: 1;
    width: 75px;
}

.dropdown-menu li {
    color: darkslategrey;
    display: block;
    text-align: center;
    padding: 5px;
}

.dropdown-menu li:hover {
    background-color: snow;
    cursor: pointer;
}

/* form:valid>.dropdown:hover .dropdown-menu */

form:valid .dropbtn:focus+ul.dropdown-menu,
form:valid .dropbtn:active+ul.dropdown-menu {
    display: block;
}

ul.dropdown-menu:active {
    display: block;
}

form:valid .dropdown:hover .dropbtn {
    background-color: white;
}

form:invalid .dropbtn {
    background-color: rgb(255, 229, 226);
    border-color: rgb(236, 187, 182);
    color: lightgray;
    cursor: default;
}