form {
    display: flex;
    flex-direction: column;
    max-width: 800px;
    margin: auto;
}
.form-row {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-bottom: 15px;
}
.form-group {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 250px;
    margin-bottom: auto;
}
.checkbox-group {
    margin: auto;
}
input[type="text"], input[type="email"], input[type="tel"], input[type="date"] {
    width: 100%;
}
input:focus {
    outline: none;
    border-color: black;
}
#postal-code-group, #birth-date-group {
    min-width: auto;
    max-width: 150px;
}
#number-group, #extra-group {
    min-width: auto;
    max-width: 100px;
}
@media only screen and (max-width: 800px) {
    #postal-code-group, #birth-date-group {
        max-width: 100%;
    }
    #number-group, #extra-group {
        max-width: 100%;
    }
}