So I am doing a basic html site, and I use a three columns layout, but I don't want the background of the columns to be opaque. How can I change the transparency? Here is a relevant part of the code:
<div class="row">
<div class="column left" style="background-color:#aaa">
<h2>Column 1</h2>
<p>Some text..</p>
</div>
<div class="column middle" style="background-color:#bbb">
<h2>Column 2</h2>
<p>Some text..</p>
</div>
<div class="column right" style="background-color:#ccc;">
<h2>Column 3</h2>
<p>Some text..</p>
</div>
</div>