problem description

@component-namespace lu{
    @b row{
        box-sizing:border-box;
        position: relative;
        @utils-clearfix;

        @m flex{
            display: flex;
            &::after,
            &::before{
                display:none;
            }
        }
    }

I use this way to vscode error
Unknown at rule @ component-namespace
how to solve this, and the highlight of the code is not normal

what result do you expect? What is the error message actually seen?