If it's shown in Cocos Creator itself, it means there is some problem with your graphic card, maybe reinstall the driver can fix it.
If you want to run Cocos Creator projects with Canvas runtime in browser, in the build path, you will find main.js, in which you can add a
renderMode property to
option, and set it to 1. Then your project will be forced to render in Canvas mode.
In v1.0, we will provide the possibility to modify the predefined templates.