Have you tried Themes found here : copy/paste about:addons in the address bar and enter, click Themes and will find the Default. Note: more themes will be available in the near future.

Please let us know if this solved your issue or if need further assistance.

I have tried all 3 available themes and do not like any of them though the light one works best for me of the three. Thank you for your rapid response!

go to the 3 Bar Menu top right side, Click and then go to Optimize Look a the the bottom of the page and will see Themes, there are more listed there and more will come. https://www.howtogeek.com/333110/how-to-customize-firefox-quantum-and-remove-the-white-space-around-the-title-bar/

This may help you feel more comfortable :

Here's a more comprehensive project which affects not only tabs but brings back the old "grid-style" options menu. https://github.com/axydavid/FirefoxUI/blob/master/README.md

It isn't completely possible to use the Australis design with Firefox 57, but depending on what you want, you might be able to customize the UI to look more like the old one: This project: https://github.com/wilfredwee/photon-australis lets you have the old tab bar appearance back in Firefox 57. You can remove the space around the address bar by right-clicking on the spaces, and choosing "remove from toolbar". Note the Black Theme is just a Example and can be found in Customize.

Please let us know if this solved your issue or if need further assistance.

These look like some interesting options and something to experiment with over the long weekend. Thanks!