Question

How would I select only the first level .block and not any of the children?

$('.block:not("Children of this here")') <–

<div class="block"> <!-- this -->
  <div class="block"> <!-- not this -->
    <div class="block"> <!-- not this -->

    </div>
  </div>
</div>

<div class="block"> <!-- and this -->
  <div class="block"> <!-- not this -->
    <div class="block"> <!-- not this -->

    </div>
  </div>
</div>

Answer 1

If that sample markup has a parent element, for example below. If not, the parent will be body if it is valid HTML.

HTML

<div id="parent">
<div class="block">
  <div class="block">
    <div class="block">

    </div>
  </div>
</div>
</div>

jQuery

$('#parent > .block').css({ border: '1px solid red' });