Java web development notes (8) strange problems

1. Some CSS styles are easy to use directly in the html style, but cannot be used in the CSS file.

If the css file name is correct when referenced, then it is the id that starts with the number, and the class is named

Reference: https://zhidao.baidu.com/question/329453141.html

Don't use numbers as style names, use a letter starting with a style name. For example, div18.
<style>
.div18{font-weight:bold; font-size:18px;}
</style>
<div class="div18"> ddddd</div>
This, also check that the CSS path of your LINK is correct.