sass

1.sass css互转

sass to css：https://www.sassmeister.com/

css to sass：http://css2sass.herokuapp.com/

2.vue3配置sass 

vue create <project>

选择： Manually select features
下一步： CSS Pre-processors
下下一步：Sass/SCSS (with dart-sass)
最后配置：

<style type="text/scss" lang="scss" scoped>
    a {
        color: pink;
        &:hover {
             color: green;
         }
    }
</style>