Wage gap maximum.
In a nutshell the law would make it illegal to pay the top earner of the company x% higher than the lowest paid employee.
This would force companies to give raises to the bottom level in order to give pay raises to the top level.
This would also mean that employees would actually see the fruit of their labor pay off. It may actually give people incentive to work harder instead of getting by with the minimum work to not get fired. A win win for everyone.
How much of a gap allowance is debatable, but any gap max would be better than none.
And yes things like stock options and valuable assets would count as income to prevent cheating the system.