diff --git a/components/style/custom_properties.rs b/components/style/custom_properties.rs
index 7be700ec350..2efcda9ef15 100644
--- a/components/style/custom_properties.rs
+++ b/components/style/custom_properties.rs
@@ -64,6 +64,20 @@ fn get_safearea_inset_right(device: &Device) -> VariableValue {
     VariableValue::pixels(device.safe_area_insets().right)
 }
 
+fn get_content_preferred_color_scheme(device: &Device) -> VariableValue {
+    use crate::gecko::media_features::PrefersColorScheme;
+    let prefers_color_scheme = unsafe {
+        crate::gecko_bindings::bindings::Gecko_MediaFeatures_PrefersColorScheme(
+            device.document(),
+            /* use_content = */ true,
+        )
+    };
+    VariableValue::ident(match prefers_color_scheme {
+        PrefersColorScheme::Light => "light",
+        PrefersColorScheme::Dark => "dark",
+    })
+}
+
 static ENVIRONMENT_VARIABLES: [EnvironmentVariable; 4] = [
     make_variable!(atom!("safe-area-inset-top"), get_safearea_inset_top),
     make_variable!(atom!("safe-area-inset-bottom"), get_safearea_inset_bottom),
@@ -99,7 +113,7 @@ macro_rules! lnf_int_variable {
     }};
 }
 
-static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 5] = [
+static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 6] = [
     lnf_int_variable!(
         atom!("-moz-gtk-csd-titlebar-radius"),
         TitlebarRadius,
@@ -121,6 +135,7 @@ static CHROME_ENVIRONMENT_VARIABLES: [EnvironmentVariable; 5] = [
         GTKCSDMaximizeButtonPosition,
         integer
     ),
+    make_variable!(atom!("-moz-content-preferred-color-scheme"), get_content_preferred_color_scheme),
 ];
 
 impl CssEnvironment {
@@ -328,6 +343,11 @@ impl VariableValue {
         })
     }
 
+    /// Create VariableValue from an int.
+    fn ident(ident: &'static str) -> Self {
+        Self::from_token(Token::Ident(ident.into()))
+    }
+
     /// Create VariableValue from a float amount of CSS pixels.
     fn pixels(number: f32) -> Self {
         // FIXME (https://github.com/servo/rust-cssparser/issues/266):