Styling checkboxes that are even children

I have a whole bunch of checkboxes and want to style all the ones that are even children i.e 2nd, 4th, 6th, 8th.

I have tried doing the following but to no avail.

.basic li > di开发者_如何学Pythonv .choices input[type="checkbox"] {
    width:14px;
    height:14px;
    float:left;
    border:0 none;
    background:#fff;
    padding:0;
}

.basic li > div .choices input[type="checkbox"]:nth-child(2n-1) {
    margin:0px 0px 0px 60px;
}

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Use :nth-child(even) or :nth-child(2n+0) (any calculation resulting in an even integer) according to:

http://www.w3.org/TR/css3-selectors/