How to type the sentence "Day students, please show your health code" in css?

This is a simple example, you can change it as you like

lt;!DOCTYPE htmlgt;

lt;htmlgt;

lt; headgt;

lt;meta charset="utf-8"gt;

lt;titlegt;demolt;/titlegt;

lt;style type=" text/css"gt;

body{position: relative;}

body::before{content: "Day students, please show your health code"; position: absolute; top: 0; left: 0;}

lt;/stylegt;

lt;/headgt;

lt;bodygt;

lt ;/bodygt;

lt;/htmlgt;