/* all */
a {
    color: blue;
    text-decoration: none;
}
a:hover {
    color: purple;
    text-decoration:underline;
}

/* form */
.form-group {
    margin-bottom: 1.5rem;
}
.form-group.valid input {
    border-color: green;
}
.form-group.invalid input {
    border-color: red;
}
.form-group small {
    visibility: hidden;
}
.form-group.invalid small {
    visibility: visible;
    color: red;
}