WorkIt Landing page with desktop, tablet, and mobile responsive design

Feedback is very welcome and appreciated. I'm new to html & css, and some things I"m not sure of include:

-organizational structure of html code and css classes. Was I right to place the content on the page in a content wrapper ?

• fairly certain I could use some clarity on unit usage on elements and their parents / children (em, rem, %, vw, vh, etc)