Responsive Design

My youngest started first grade this year and needs some tool to help him study so I decided to create a quiz app in a browser for him. So it was time for me to brush up on html, css and JS. I have some basic code in Javascript for randomly picking the questions and keeping track of the score and the rudimentary page layout done. Next comes the requirement to be able to use the quiz on different platforms like tablet and laptop. This is where the idea of responsive design comes in which is new to me. I haven’t created a site since the early 2000s.Since then I have been using platforms like WordPress or SharePoint. For most of my simple use cases this is more than sufficient but using WordPress or Sharepoint to put content online doesn’t generate the understanding you need if you have to build something from scratch. So now I find myself going back to the core of html, css and JS to discover how much has changed over the last 25 years. And luckily now you don’t need a book to learn about things if you are just looking for bits and pieces. For responsive design and the use of relative units in css I got a few helpful links.
1. w3school article on css units
2. em and rem
3. px for root; rem for modules and em for text element sizing