"Kind of Pop-up Button"

Hi, i want to create this Login-Button:
www.ogame.org (ogame.org)
Can you give me an idea how that works?
Thank u, nvidia

It's just a <div> that is floated over the top of the rest of the page by (a) giving it an absolute position and (b) a z-index higher than the rest of the page.

When you click on the button, it probably changes its style.display property from "none" to "block" (and also changes the text in the button).

Not terribly hard; hardest part will be creating the pretty graphics to make it look good.

it works, awesome =)