CSS trends with naming class and id with dash underscore?
<p>I've been using dashes as a separator for css Class and ID names:</p>

<pre><code>.about-us
.car-pricing-guide
</code></pre>

<p>I've seen sites use multiple underscores <code>__</code> </p>

<pre><code>.home__content
</code></pre>

<p>Also, I've seen 2 dashes</p>

<pre><code>.hero--title
</code></pre>

<p>I know it's a matter of preference but can someone point to articles or the though process for these kind of patterns? Is there a move towards a particular convention or is there a popular set of convention people seem to agree/follow?</p>