Steps to reproduce

• add code block with

  <h1 class="display-1">I LOVE NY</h1>
  

• add custom css (block level)

  h1.display-1 {color: red}
  

• Submit, h1 is red
• Publish page, h1 is not red anymore

Issue

Code generated:

<style type="text/css">[data-block-id="46"] h1.display-1 {
  color: red; }
</style>

It should be

<style type="text/css">[data-ez-block-id="46"] h1.display-1 {
  color: red; }
</style>