CSS changes the font size without affecting the webpage

We use CSS in the webpage to set the webpage, table, and font size. Generally, we use 9-pound words that are popular on the Internet:
<STYLE type = TEXT/CSS>
BODY {COLOR: # ff0000; FONT-FAMILY:; FONT-SIZE: 9pt}
</STYLE>
In CSS, I set FONT-SIZE to 9pt. When the display is set to a small FONT, we can see the small five FONT display, however, in a computer with a large font, the page will become 11 lbs, and the page will naturally be messy.
CSS can recognize multiple numeric units. There are generally two common units used to determine the text size: pt (points) and px (pixels ). Pt indicates the dot matrix font in text mode, while px indicates the pixel unit of the screen. Since all computer systems support px units, the resolution of the display screens on each computer is different, but the difference in the resolution of the computer is not very obvious, therefore, this problem is well solved. There is a simple conversion relationship between them, that is, the pt unit multiplied by 4/3 is the px unit. Therefore, you can solve this problem by setting the FONT-SIZE of the webpage to 12px (the same SIZE as 9pt. Set it to a large font. It is no different from a small font!