diff --git a/components/atoms/static_atoms.txt b/components/atoms/static_atoms.txt
index 5163b943fef..5d8f7754270 100644
--- a/components/atoms/static_atoms.txt
+++ b/components/atoms/static_atoms.txt
@@ -125,6 +125,7 @@ safe-area-inset-right
 scan
 screen
 scroll-position
+scrollbar-inline-size
 search
 seeked
 seeking
diff --git a/components/style/servo/media_queries.rs b/components/style/servo/media_queries.rs
index 269c8a5c056..4140b1fd378 100644
--- a/components/style/servo/media_queries.rs
+++ b/components/style/servo/media_queries.rs
@@ -164,6 +164,12 @@ impl Device {
         self.device_pixel_ratio
     }
 
+    /// Gets the size of the scrollbar in CSS pixels.
+    pub fn scrollbar_inline_size(&self) -> CSSPixelLength {
+        // TODO: implement this.
+        CSSPixelLength::new(0.0)
+    }
+
     /// Queries dummy font metrics for Servo. Knows nothing about fonts and does not provide
     /// any metrics.
     /// TODO: Servo's font metrics provider will probably not live in this crate, so this will