In order to achieve user interaction on a webpage, JavaScript is essential.
JavaScript is specifically designed for user interaction, while CSS primarily focuses on presentation. This means that CSS has limitations when it comes to interactions (for example, it can respond to hover actions but not click actions in the expected way).
One possible workaround is using a checkbox to control "click" states and then displaying something based on that status using CSS.
To implement this solution:
<label><input type="checkbox">My link
<p>Sed ut perspiciatis unde omnis iste natus</p>
</label>
The corresponding CSS would look like this:
input[type="checkbox"] {display: none;}
input[type="checkbox"] + p {display:none; margin-left:1em;}
input[type="checkbox"]:checked + p {display:block;}
If you want to see an example of this in action, check out this Fiddle.
Keep in mind that while this approach may work, it may not be fully compatible across all browsers, so ultimately resorting back to JavaScript might be necessary. ;)