step 1: create a new css file in the page or pages directory, such as style.css;
step 2: import the css file in the jsx page, for example:
import style from './style.css';
Step 3: Add the className attribute to the complex you need to decorate, for example:
className={style.sty1}
Step 4: Define the className property in the css file, for example:
sty1{color:red}