About UL inside the Li floating behind the P is not exclusive line of the problem

Why the LI element inside the UL floating up after should be exclusive line of P tag will follow up with the content of Li element? Introduced a CSS inside put unless set UL line high, so that P tag will drop, this is why?

It came out without a CSS effect.

I was bored at first, but then I looked at the information and knew what was going on. This is because the float makes Li out of the normal flow of the document, Li's parent element ul's height becomes 0, then the position of the P element adjacent to the UL is up. And because the float will indent the neighboring content, so the text inside the P element will be affixed to Li, if the text in the P element is enough, you will see that the text in the P element is surrounded by Li, which is the most essential work of floating. When you set the UL height, some properties of UL are no longer affected by the float, p therefore went down. So after the floating used to pay attention to, accidentally on the trick drops.

About UL inside the Li floating behind the P is not exclusive line of the problem