my header seems to be fixed (position) I want it to be relative to the slider images. So the header isn't in a weird spot.

I still don't get it...it looks fine.

Your logo / tabs are stopping it from moving left if that's the issue.

He wants the logo to stay in the same position in relation to the image carosel, when the window gets narrower, however looking at the DOM simplest way I can think of is to wrap another div around the header and the slider and center that using the margin: 0 auto;

That or drop the logo's div into the slider's div and use absolute to position it as it would be normally.

Eitherway feels like its a bit hacked. And the second won't work cus I just noticed the overflow hidden

try adding or changes these pieces of css

  #header.gallery {
      width: 1020px; /* Same width as the slider has */
  }

  #header-logo {
      width: auto;
      margin-left: 130px;
  }

  #tabs {
      right: 0;
      margin-left: auto;
  }