Nowadays, HTML5 is attracting more and more attention, but browsers that support HTML5 are not yet mainstream. In particular, nearly 50% of domestic users still use IE6. Since IE9 that supports HTML5 does not support Xp system installation, this will affect the future For a long time, HTML5 developers will have to consider backward compatibility issues. There are many ways to achieve HTML5 tag or CSS selector compatibility, one of which is generating tag elements yourself.
For the basic principle, see the effect of the following code in IE8, the style has no effect at all.