diff --git a/components/style/custom_properties.rs b/components/style/custom_properties.rs
index df3f9660dd4..a6908bb4cfa 100644
--- a/components/style/custom_properties.rs
+++ b/components/style/custom_properties.rs
@@ -71,10 +71,19 @@ static ENVIRONMENT_VARIABLES: [EnvironmentVariable; 4] = [
     make_variable!(atom!("safe-area-inset-right"), get_safearea_inset_right),
 ];
 
+static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 0] = [
+];
+
 impl CssEnvironment {
     #[inline]
     fn get(&self, name: &Atom, device: &Device) -> Option<VariableValue> {
-        let var = ENVIRONMENT_VARIABLES.iter().find(|var| var.name == *name)?;
+        if let Some(var) = ENVIRONMENT_VARIABLES.iter().find(|var| var.name == *name) {
+            return Some((var.evaluator)(device));
+        }
+        if !device.is_chrome_document() {
+            return None;
+        }
+        let var = CHROME_ENVIRONMENT_VARIABLES.iter().find(|var| var.name == *name)?;
         Some((var.evaluator)(device))
     }
 }
diff --git a/components/style/gecko/media_queries.rs b/components/style/gecko/media_queries.rs
index 2f5a9673d4c..2966363a8eb 100644
--- a/components/style/gecko/media_queries.rs
+++ b/components/style/gecko/media_queries.rs
@@ -439,4 +439,10 @@ impl Device {
             bindings::Gecko_IsSupportedImageMimeType(mime_type.as_ptr(), mime_type.len() as u32)
         }
     }
+
+    /// Return whether the document is a chrome document.
+    #[inline]
+    pub fn is_chrome_document(&self) -> bool {
+        self.pref_sheet_prefs().mIsChrome
+    }
 }