Hello,
For those of you who want to test out your Sightly code in a simple web based tool, I recommend you install this. You can browse to http://localhost:4502/content/repl.html and just delete the existing statements and see the outputs on your page. It is very useful and the Maven project is here:
https://github.com/Adobe-Marketing-Cloud/aem-sightly-repl
To install it, simply execute the command using maven:
mvn clean install content-package:install