CSS only thumbnail slider
I'm trying to make a thumbnail which on hover will move it's image (that's longer that the wrapper) all the way to the left using only css and using the img element and not a div with background-image.
The problem I have is that i don't know how could I find how much to move it given the fact that the images have different widths.
I did a demo where the left image moves correctly because I calculated how much it needs to be moved and the right image with the same css moving incorrectly: http://jsfiddle.net/g5JGd/1
It's not clear why you're restricting yourself to manipulating the img element alone and not exploring more usual background-image sprite-like hover event manipulations.
The techniques offered don't produce the exact end result you're after, but they do include the structure for the type of events and manipulations you'd need to use.