CSS rotation with respect to a reference point

You could use transform-origin. It defines the point to rotate around from the upper left corner of the element.

transform-origin: 0% 0%

This would rotate around the upper left corner.

For other options look here: https://developer.mozilla.org/en-US/docs/Web/CSS/transform-origin

for the safer side if this link not available then here are a couple of more options

transform-origin: center; // one of the keywords left, center, right, top, and bottom

transform-origin: top left; // same way can use two keywords

transform-origin: 50px 50px; // specific x-offset | y-offset

transform-origin: bottom right 60px; // third part is for 3D transform : z-offset

As far as I know there isn't an option to rotate around a fixed point (although this would be handy).

If you need a specific offset, one way is to edit your image to make it larger, such that the centre lies in the middle of your image. You can then place this within a DIV with "overflow: none" and position it with relative positioning. The div will mask off the area of the image you don't wish to display.