CSS onclick

It is possible simulate onclick behaviour using checkbox:checked pseudo class

HTML

<label for="checkbox-trigger"><span class="trigger">Trigger</span></label>
<input type="checkbox" id="checkbox-trigger">
<h3>Targets</h3>
<span class="target">Target 1</div>
<span class="j">Target 2</div>
<span class="j">Target 3</div>

CSS

#checkbox-trigger:checked ~ .target {
    background-color: #0f0;
}