Open-source UI framework and components for HTML5 hybrid mobile app development, based on PhoneGap / Cordova.
It allows developers to create mobile apps using Web technologies like CSS, HTML5, and JavaScript.
TO convert web app into Native app:
tools you can use to turn your .html/css into an android app(.apk file):
phonegap(+ nodejs)
intel xdk
cordova
visual studio + cordova
CSS Components:
refer this link:
https://onsen.io/v2/api/css.html
Javascript component:
refer this link: