How to set the position

http://www.kampyle.com/ in this url when you scroll one picture always moves. I want to know this process name. How can they do it? After clicking this picture it's vanished and never appears even on refreshing the page. How do they get information that I clicked this picture? It will开发者_StackOverflow社区 be helpful for me if someone gives me the solution.

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If you mean the feedback button that remains on the bottom right corner, here is the CSS you need:

.button{
    z-index: 9999999;
    position: fixed;
    right: 0;
    left: 0;
}

With this code you can have a fixed image on the bottom right corner:

<img src="feedback-button.gif" class="button" alt="Feedback button" />

BUt I don't see how the button is vanishing. I am quite sure that they have done it using a cookie or a session varibale which will pervent the button to appear on the next load of the page.

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They just set the anchor that contains the image to:

position:absolute;
right:0;
bottom:0;

It's called absolute positioning.

As for only showing it once, that can be handled with a cookie or with a session variable.