title: Why does Markdown in Jupyter Notebook represent these Horizontal Rules differently with the same input?
body: <p>In my Juptyter notebook I have many horizontal rules (generated in markdown cells) to break up the blocks of code, to create the horizontal rule I am using 3 underscores "___". For some reason, which I cannot figure out, the line sometimes appears as dark grey and sometimes as light grey.</p>
  
  <p>In the screenshots below you can see the same "___" produces two differently colour lines.</p>
  
  <p>Does anyone know the reason? Ideally i'd like them all to be the darker grey</p>
  
  <p><img src="https://i.stack.imgur.com/1ZSux.png" alt="markdown code I am entering"></p>
  
  <p><img src="https://i.stack.imgur.com/36885.png" alt="different coloured lines produced"></p>