Why does the header not cover the blocks included in it?

Question

PHP

Guys, there is a header which is 0 in height, although it has blocks, how to make its height depend on the blocks in it?
SAM CODE , if something gives.
CMS opencart.

Answer 1

Wangyu needs a clearfix

Answer 2

Before the closing header put.
You used a float and didn't close it, so it affects the header.
Here - codepen.io/anon/pen/QyxVjL - added a black background to be seen.