Xtend is a universal display scaling solution, which means it works with all platforms out of the box. This includes HTML5, which in turn supports virtually any device with a web browser. However, using HTML5 also turns certain scaling duties over to the web browser--namely, DPI scaling.
If you find your application appears blurry when running in HTML5 on high-DPI devices (e.g. most modern smartphones), you must configure your project to override the browser's DPI scaling for consistent results.
Global Game Settings > Platform Settings > HTML5 > General > Prepend output .js with
This will allow the application to display at full resolution regardless of DPI.