html – Why the text of my in navi bar cannot go horizontal after I css define then as float:left? what’s going on with my coding. Can someone help?thx

Why the text of my<li></li> of navi bar cannot turn into horizontal after I code in css,and define them as
{ float:left } ?

What’s going on with my coding. does someone has the same situation at the beginning of html css? please advise me a mentor that can revise my code thx!