Is there any guideline to make sure a web page built by outsystems studio has the same look on any major browser?  [e.g. Like what component shouldn't be used, which layout wouldn't work in certain browser...etc]  

One of our vendors are helping us writing a web app and we found it looks good on chrome but quite terrible on IE 11.  But the web demos I downloaded from Forge don't have this problem.

Hi William,

IE shouldn't be used. Even MicroSoft itself says so. OutSystems 11 also doesn't support IE very well. Stick to Chrome, FireFox or Edge and you'll be fine. All OutSystems components from SilkUI/OutSystemsUI should work in all browsers.