CSS can't be found



I have try all idea and read all related article, but still can’t find the answer.

I put my css file and html file in the same folder, and use href=“base.css”, like following code

but the error message always return these words.

Not Found: /base.css
[30/Sep/2017 15:12:53] “GET /base.css HTTP/1.1” 404 2049

yes, it is like why it have the “/” before css file.

please have some idea for this, thanks.