I have created a fixed header by adding #header {position:fixed; z-index: 25;} to the
Add HTML/CSS Inserts but it is not responsive. I have tried editing the Style and Edit Header area by adding width: 100%; in several areas as will as adding the width to the #header entry but I can not get it to be responsive.

What am I missing?

Thanks,

Dan

Solved it, Under Style and Edit Header Area>Logo Image: Styling I added:

width: 100%; height: 100%;

I now have a fixed responsive header.

Actually that didn't work, when viewed on a cell phone it did not look good, I had to remove the height: 100%;

You might want to add some media specific CSS