We'll create fresh WordPress site with Cookie Message installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Cookie Message plugin will on activation add a message at the bottom of your screen.
When clicking the button it will disapear. How long is for you to decide but default is forever. It will remember it by HTML5 localstorage, not by a cookie.
You have settings for information that goes into the message, colors, fonts and you can disable CSS and javascript if you need to. See screenshots for more information about the settings.