Add cookie dialog

I need to add a cookie dialog to my pages. I have a specific requirement how this dialog
should look like. I don't want you to implement it anew, I just want to use an existing
component or library. It should be free or cheap.
The dialog should be a bar that sticks to the bottom of the screen. The dialog will
contain 2 buttons (Accept all / Necessary only) and some text like This page is using
cookies. All texts customizable somehow easily. Colors and styles in some CSS file, i.e.
customizable as well.
The bar would appear when a JS function gets called and hide after the user clicks
a button or some other function gets called (so the main page Javascript will be able
to show/hide the bar and the bar). Clicking on buttons will hide the bar and call
a configured callback.
The bar will not do anything else, will not set any cookies or whatever. Just do what
I describe here. The output that I need from you is a Hello world simplest possible
HTML page with the bar integrated and a description how to integrate it into any
other page.