title: How to reset jupyter notebook theme to default?
body: <p>I'm using the jupyter notebook installed with Anaconda (I'm on Mac). Few days ago, I wanted to change the theme to have a dark background, and I followed the <a href="http://sherifsoliman.com/2016/01/11/theming-ipython-jupyter-notebook/" rel="noreferrer">instructions here</a>. Namely, I've downloaded the theme <code>custom.css</code> and placed it in <code>~/.jupyter/custom/</code>. It worked very well. </p>
  
  <p>I liked the theme, but I would like to go back to the default one (this one does not show the main toolbar, among other things). I tried to remove the <code>custom.css</code> from its folder, I reset my terminal, but nothing changes! I'm guessing that jupyter keeps a copy of the themes somewhere that I should delete, but I can't find it.</p>
  
  <p>I have also tried uninstalling jupyter and reinstalling, following the commands:</p>
  
  <pre><code>conda update conda
  conda uninstall ipython
  conda install jupyter
  </code></pre>
  
  <p>Again, no change. I'm stuck with my black background theme with no toolbar.</p>