That's my header image.
Also, why change the style from 100% to 86px? We're trying to make a div with an image in it that will stay 100% both directions in any resolution.
That's what I've been doing, only when I saw my site on a large monitor, I realized that at very high res a fixed background image is just centered in the page. On a small page, you only see part of a background image. I really like the way it looks, and I'd like it to look the same way everywhere, so I'm trying to make an elastic background image. I found a way to do this using css and html. Now I'm trying to figure out how to make it work with WordPress.
And here's where things get VERY ODD. I got it to work, and then it quit working. What made it work was dropping the div with the actual image on the index page and, ARGH!, setting the style z-index to -1. It took seven hours for me to realize that maybe you could go below zero with a layer. And it really, really did work. Perfectly. Looked just like a background image, only I could resize the window any which way and the image got larger and smaller with it. I got to see it working this way many times.
I noticed my text had shrunk somewhat, and thought it puzzling, but didn't pay much attention. Then, I noticed that my background image had "short pants" if the page loaded in any way other than clicking reload. Like, clicking one of the internal links back to the index made the background image too short. It was retaining its scale for some reason. Like, the purportions of the background image stayed the same and so it didn't fill the page. But if I just clicked reload, it continued working right (didn't scale). Again, I did this many times.
And then, all of a sudden, my font returned to its normal size and the background image never reaches 100% vertically anymore no matter what. Also, it's no longer scaling when I resize the window. Bear in mind, there's no reason for a background image to even appear except for that div, so it's not like I'm seeing a "real" background image -- I took it out before I started all this.
To make matters EVEN WEIRDER, some of my theme's default settings that I changed WEEKS AGO have come back. Styles I haven't been anywhere near.
I have no idea what's going on anymore. It's like I have a haunted website.
Does WordPress ever "fix itself" or something?