HTML content in Model Popup

Aim - I want to make a button, and after clicking that button a model popup should display a information written in HTML.

Step 1 ; I have taken a mashup then a html text area widget on that mashup. 

Step 2 : I have created a thing in which I have written a service that gives a html output (Example service is written below). 

Step 3 : Bind the output of the service on the widget created in step1 mashup.

step 4 : Now from widget take a button in some mashup, then create a function - navigation and select as model popup and navigate to mashup created in Step 1.

Example Service:
let content ="<h1>Rules and Regulations</h1>"+
 "<p>Employees must follow all safety protocols and procedures.</p>"
;
result = content ;