The Ionic Framework is an open source mobile UI toolkit for building high quality, cross-platform native and web app experiences using a single codebase. It has standard reusable components which work on all platforms which can be used to write Mobile, Progressive Web, or Desktop applications. It makes use of Adaptive Styling to look at home on each of these platforms. And has a developer friendly tooling for cross-platform deployment.
zen.digital offers a 2 day Ionic training plus can offer supplemental supporting classes.