Learn how to clear floats with the "clearfix" hack.
Read on how to do it in this tutorial: https://www.w3schools.com/howto/howto_css_clearfix.asp
How To Clear Floats (Clearfix)
Elements after a floating element will flow around it. Use the "clearfix" hack to fix the problem:
Try it yourself here: https://www.w3schools.com/howto/howto_css_clearfix.asp