Generated by SassMeister.com.

input.scss

dl.definitionList {
  @at-root #{&}--vertical.#{&}--compressed {
    dd {
      border: 1px solid red;
    }
  }
}

output.css

dl.definitionList--vertical.dl.definitionList--compressed dd {
  border: 1px solid red;
}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.26.11",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}