@media only screen and (max-width: 540px) {
    #loginForm, #registrationForm { width: 100%; margin: 0; }
}

/* quiz form */
.form_quiz {
    label {
        display: block;
        margin-bottom: 10px;
        padding-left: 20px;
    }

    input[type="radio"], input[type="checkbox"] {
        margin-left: -21px;
    }
}