WebGL Responsive Layout

I have been fighting this for days now and cannot seem to find any good solution. I am trying to build to WebGL and host on site and allow for desktop and mobile users to access the game. On mobile however I cannot get it to size properly. I have tried multiple different changes in Unity and in CSS and nothing works. I have done anchors, auto sizes, HTML and CSS heights and widths ect. I am using Unity 6 so I cannot find a web template that will do this for me that is compatible.
Looking for some direction, help, advice, ect. Thanks!