It is absolutely OK to have a bottom Tab Bar on a website! There are many benefits to it but the most important benefits of a Mobile Navigation Menu at the Bottom of the screen are:
👍 When the Navigation Menu of a website is positioned at the Bottom of the Screen it provides OPTIMAL THUMB ZONE ACCESS.
👍 The Thumb Zone Friendly Ambidextrous Mobile Navigation Menu provides OPTIMAL THUMB ZONE ACCESS to both the LEFT and RIGHT hand THUMB FINGERS.
👍 My website uses the SAME WEB PAGE LAYOUT AND MENU NAVIGATION that can scale from a small Smartphone screen to a Large Screen TV without using CSS3 Media Queries and is compatible with web browsers running BOTH CURRENT AND OLDER VERSIONS of Apple, Android an Windows operating systems.
👍 VisitMy website uses this feature: https://raulgonzalez.com/thumbzone.php and you will see it in action!
Thanks
Raul Gonzalez