Using the following style, we see the animated eye.gif in the top right corner of the page.
Since we used background-attachment: fixed;, it stays in position even
if we scroll down the page...

body {
  background-image: url(eye.gif);
  background-repeat: no-repeat;
  background-position: right top;
  background-attachment: fixed;
}

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

Extra text, so you can scroll down the page.....

We never know who is watching :^)