In this example I want to rotate the hammer from its bottom so is there a way to know exactly the right coordinates of a specific point on the element or should I randomly t
transform-origin:[x][y]
replace x and y with percentage values like 50% for mid, 0% for start and 100% for ending positions respectively. I’ve made a pen for helping you to understand this once and for all.
I wrote a complete article here: https://medium.com/@RajaRaghav/understanding-css-transform-origin-property-2ef5f8c50777 with illustrative examples