Generated by SassMeister.com.

input.scss

$breakpoints: (phone: 320px, tablet: 768px, desktop: 1024px);

@container foo (<= #{map-get($breakpoints,"phone")}){
    
}

output.css

@container foo (<= 320px) {}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.32.12",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}