apply same css styles to divs in the arithmetic sequence of three

I have 10 items in my database table. I want to apply same CSS style to the divs in the arithmetic sequence of 3 items.

For example, items [0, 3,6,9] will have css style slideInDown, items [1,4,7] will have css style slideFloat and items [2,5,8] will have style slideInUp.
@if ($i % 3 == 0), I think this will satisfy the series [0, 3,6,9] but how to write logic for other two series.

My code::

@for ($item = 0; $item < count($posts); $item++)
    @if ($i % 3 == 0)    <!-- for items [0,3,6,9]  -->                
        <div class="content">
            <div class="slideInDown text-center">
                <p> $posts[$item]['post_content'] </p>
            </div>
        </div>
    @elseif($i == 2) <!-- what will be logic for items [2,5,8]  --> 
        <div class="content">
            <div class="slideInUp">
                <p> $posts[$item]['post_content'] </p>
            </div>
        </div>
    @else  <!-- for items [1,4,7]  --> 
        <div class="content">
            <div class="slideFloat">
                <p> $posts[$item]['post_content'] </p>
            </div>
        </div>
    @endif
@endfor