Remove gap that header left

I have used the browser_mod integration to remove the header from my browser. This works great, but I’m not sure how to remove that large gap that was left behind where the header was.

I found this on Google, but not sure if it really works or where I need to add this. It’s a bummer you can hide the header information, but that space is still being taken up at the top of the dashboard. I tried to add this to the begining of my dashboard, but did not see any change. No error, but not change either.

browser_mod:
  - module: custom_css
    css: |
      .header {
        display: none;
      }
      .header-container {
        display: none;
      }