html - 我的 Html/CSS 代码中有这个三角形，但我不知道那是什么

Question

看看这个

  th.asc a:after {
    content: '▲';
}

可以在键盘上键入什么可以使该符号出现？这个符号是什么？我应该什么时候使用它？

Answer 1

该字符将在<a>标签内的th标签之后呈现，并且可能查看您的类名asc它表示升序排序，它仅用作表示升序排序的图标

更多关于 CSS内容属性

关于三角形字符的信息

th.asc a:after
     ---^---
/* This makes the content character render after the <a> tag which is inside 
   th having class .asc which I assume stands for ascending, if you use :before 
   instead of :after, triangle will be rendered before the <a> tag text */

Answer 2

It is a Unicode character, that besides giving support to all the different alphabets in the world, have graphics chars.

You have a lot of pages to look for unicode characters. One specially curious is

shapecatcher

where you can draw the shape that you wanty.

Specifying them in the CSS is easy, you just have to put the number behind a backslash

'\25A0'

is a square