Why does the adjusted function use pixels as a unit of measurement when the objective is to make the position of each 'click zone' show correctly? Is that not was percentages are for? ie. You have

    var steps = [
     ['/img/flow/click-users.png', [1, 280]],
     ['/img/flow/click-header.png', [765, 155]],

Where the array is x,y coords in pixels? Why would you not use percentages instead for the top and left offsets? I see your adjusted function is getting the correct offset for the screen aspect ratio, but wouldn't you get the same result on percentages?