You should be able to add a custom Class name to one or both table stacks. Then you’d be able to add the custom class name to the css selectors.
So for the league table stack you could just add a class name of league (there should be a place in the stacks settings to add the class name).
Then for the css that’s specific to the league table you would add the league class (preceded by a period)
.league .col1 { width: 20% }
There might be an different way, I don’t have that stack.