The browsers are *way* more compatible than Smalltalk systems are.
I once spoke to a manager at a company I shan't name (it does not
exist any more) about a new international standard being developed
relating to their product (not Smalltalk).�� "We don't care about
the standard," he replied, "we ARE the standard."�� Come to think of
it, an open source system (again not Smalltalk) I used heavily for
a while decided to ignore the developing standard.�� That project is
dead and an attempt to revive it failed.
It's not hard to build web sites that work with the major browsers.
You just have to seriously want to.