IE11 external style sheet is invalid_html/css_WEB-ITnose

A very amazing problem
There are no problems with the two html and css texts in chrome and ff. However, after reaching IE11, the style sheet completely failed. Looking at the console, I found that the css was not loaded at all. .
Loading method

<link href="patent.css" rel="stylesheet" type="text/css">

The amazing thing is that with constant refreshing, I can load normally once every 5 times...

What’s even more amazing is that I After adding a few carriage returns to the head part of the html file to make it beautiful, no matter how I refresh it, it will have no effect.

At present, I have tried to paste the content in the css directly into the html, install it with