Edward

.clearfix:before,
.clearfix:after {
    content: " ";
    display: table;
}
.clearfix:after {
    clear:both;
}

.parent {
    display: flex;
    justify-content: center;
    align-items: center;
    align-content: center;
    flex-direction: row;
    flex-wrap: wrap;
}

.parent {
    text-align: center;
}
.child {
    display: inlide-block;
}

<?php if(isset($row)) :  ?>
                    <div class="uk-button-group">
                            <a class="uk-button uk-button-link uk-button-large" href="../auth/signup.php">Регистрация</a>
                            <a class="uk-button uk-button-success uk-button-large uk-margin-left" href="../auth/login.php" style="background-color: #ffb433;"onmouseover="this.style.backgroundColor='#eb8d00';" onmouseout="this.style.backgroundColor='#ffb433';"><i class="uk-icon-lock uk-margin-small-right"></i> Войти</a>'
                    </div>
<?php  endif;  ?>