This add-on is compatible with Concrete 5.5.
See this add-on in action: http://c5extras.com/add-ons/bounce-box/
Need an easy way to grab your website visitors' attention? The Bounce Box is ideal to draw attention to important content without affecting the layout of existing content on your page. This is perfect for promotions, special events, important news, lead generation, giveaways and so much more.
A stylish overlay appears from the top of the page with fully customisable content - you can even choose the colour of the box to match your site theme. And the best part is you can customise the frequency in which the box appears: always, once per session or randomly.