Recently I have come across a lot of posts on how to embed PowerApps into Dynamics 365 CE forms. Reading through those articles made me re imagining a solution we build back in the day using using HTML and CSS in CRM. Below are few of the Posts that became very useful to me during building this solution . What I have described is one way of doing the solution , but there can be many other ways as well  . You just have to use your imagination.

Resources

Resource 1 : How to Pass Parameters into a PowerApp

Resource 2 : Improving entity forms using embedded PowerApps (Blog Post by MVP Natraj Yegnaraman )

Resource 3 : Embedded PowerApp in Dynamics 365 CE

Resource 4 : Integrate PowerApps into websites and other service