Centering a checkbox

I can't completely (only the label is centered when I try) center this checkbox to my 'card', how can I do it ?

I tried <center>...</center> and other CSS found on Stack Overflow but no one I found are working, so I ask help here.

Source : http://ift.tt/2yU4Fe7

Code :

<div class="checkbox">
    <label>
        <input type="checkbox" value="">
        <i class="input-helper"></i>
        Don't forget to check me out
    </label>
</div>

Current CSS : http://ift.tt/2yX5LI1

Thanks in advance.