PostCSS syntax highlighting in styled-jsx does not work in VSCode

Question

PostCSS syntax highlighting is not enabled within React's styled jsx when using VSCode.

      <style jsx>
        {`
          .test {
            @apply text-red-500;

            &:hover {
              @apply text-blue-100;
            }

            & .sample {
              color: blue;
            }
          }
        `}
      </style>

I used this plugin, but it didn't work.

https://marketplace.visualstudio.com/items?itemName=cpylua.language-postcss

If anyone knows how to make syntax highlighting work, I'd like to know how to make it work.