/* VALIDATOR VISUAL */
input:required:placeholder-shown{
    border: 1px solid lightgrey;
}
input:invalid {
    border: 1px solid red;
}
input:focus:invalid {
    border: 1px solid red;
}
input:required:valid {
    border: 1px solid green;
}
input:required:focus:valid {
    border: 1px solid green;
}
input:optional:focus:invalid {
    border: 1px solid lightgrey;
}
input:optional:invalid {
    border: 1px solid lightgrey;
}