HTML

? ✕ ? ✓
? ✖ ? ✔

? ✗
? ✘

× × ×

CSS

If you want to use the above characters from CSS (like i.e: in an :before or :after pseudo) simply use the Unicode HEX value like for example:

[class^="ico-"], [class*=" ico-"]
 
{
  font: normal 1em/1 Arial, sans-serif;
  display: inline-block;
}


.ico-times:before{ content: "\2716"; }
.ico-check:before{ content: "\2714"; }
<i class="ico-times"></i>
<i class="ico-check"></i>

參考：

https://stackoverflow.com/questions/5353461/which-font-for-css-x-close-button 中Roko的回答。

css "x" button