Testet on Google Chrome Version 60.0.3112.113 (Offizieller Build) (64-Bit)
Because the colorpicker is insertet directly under the body tag in the DOM it is not updating its position when it is opened and the window with changes.
Solution may be to add 'position: relative;' CSS to the element which opens the colorpicker by click. And then define the position of the color palette absolute to the parent element. Because the parent is moved correctly when the window size changes.