Reduce space between navigation and page content

Site URL: https://www.perthsportschiro.com.au/members

Hi I am trying to eliminate the space in a red box marked in the photo. I have tried all sorts of CSS codes from the forum but nothing seems to work. Any suggestions? The space seems to above page content and I have no way of deleting it. Is there a way to do this for all webpages or just one page? I have tried doing it from the site wide Design options but nothing seems to change.

Thank you!

Did you try this in the custom css?

.Main-content {
  padding:0px !important;
}

4 minutes ago, ChrisBartow said:

Did you try this in the custom css?

.Main-content {
  padding:0px !important;
}

 

Yes I've tried that already but it doesn't work. It actually makes it worse and I end up with this blue space above the navigation