title: CSS trends with naming class and id with dash underscore?
body: <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>