CSS ”background-color” attribute not working on checkbox inside

A checkbox does not have background color.

But to add the effect, you may wrap each checkbox with a div that has color:

<div class="evenRow">
    <input type="checkbox" />
</div>
<div class="oddRow">
    <input type="checkbox" />
</div>
<div class="evenRow">
    <input type="checkbox" />
</div>
<div class="oddRow">
    <input type="checkbox" />
</div>