The Bottom-Fixed Message Bar feature in the Flex theme is an ideal way to add in a 'cookie' or 'compliance' message or any other important information that you need your customers to know about.
Enable Bottom Fixed Bottom Bar
In your theme editor (Customize), open the Layout portion of the Theme settings. Click the checkbox beside Show bottom fixed message bar to activate.
Bottom Bar Settings
Return to the main sidebar, then scroll down to the bottom to open Fixed message.
Add Text to the provided rich text field. Connect a specific page or policy by using the link feature.
Button label and style
To include a confirmation button to close it, ex. "I agree", you can enter text in the Label field.
Select Primary, Secondary, or Link style with the Style dropdown.
Select colors for the Background and Text using the provided color pickers. Adjust the Background opacity to increase transparency for the background color.
The width can either be set to Standard or Wide. Selecting Wide will spread out the full width of the screen. Selecting Standard will keep the section in a container and not spread the full width.
Add Custom CSS to the feature for further tweaking. You can even create your own CSS class here, as well. Check out this article for more information: Flex Guide: Custom CSS Feature