CSS Values 4 urls exfiltration

proposed-stylesheet.css

.body {
  --unique-identifier: 'foo' // unique generated ID
  --pointer: 'none'
  --theme-preference: 'none'
  
  // Only make one request
  background-image: url("/some/url/?" + var(--unique-identifier) + "&" + var(--pointer) + "&" + var(--theme-preference))
}

// Detect pointer type and theme
@media (any-pointer: coarse){
  body {
    --pointer: 'coarse'
  }
}

@media (prefers-color-scheme: dark) {
  body {
    --theme-preference: 'dark'
  }
}

// ...