Clipboard landing page

I left the tag on the bottom in the footer and made a div with the class of footer. That div would be the real footer. Any suggestions on how I can improve the CSS and class names, I would appreciate it. I feel like I am adding too many and I am not using parent child relationships enough.

Also, I tried using sections over divs. An article I read said that they should be used but I see that I have a warning for them. What is a section used for? Thank you in advance.