Users like nice-looking sites and web apps too. How would you make a language that allows some customization but "not enough to resemble a browser" ? Really, t

Users like nice-looking sites and web apps too. How would you make a language that allows some customization but "not enough to resemble a browser" ? Really, the only thing missing is "all popups must have browser Chrome until the user chooses to hide it for that site (or whatever the latest subset of "site" is for Origin security)