diff --git a/servo/components/style/values/computed/length.rs b/servo/components/style/values/computed/length.rs
index 819aff7c575d..cbbac910d69a 100644
--- a/servo/components/style/values/computed/length.rs
+++ b/servo/components/style/values/computed/length.rs
@@ -248,7 +248,7 @@ impl CSSPixelLength {
         Self::new(crate::values::normalize(self.0))
     }
 
-    // Returns a finite (normalized and clamped to float min and max) version of this length.
+    /// Returns a finite (normalized and clamped to float min and max) version of this length.
     #[inline]
     pub fn finite(self) -> Self {
         Self::new(crate::values::normalize(self.0).min(f32::MAX).max(f32::MIN))
diff --git a/servo/components/style/values/specified/length.rs b/servo/components/style/values/specified/length.rs
index 1b8af0280ff0..b23307c7513e 100644
--- a/servo/components/style/values/specified/length.rs
+++ b/servo/components/style/values/specified/length.rs
@@ -22,7 +22,7 @@ use crate::{Zero, ZeroNoPercent};
 use app_units::Au;
 use cssparser::{Parser, Token};
 use std::cmp;
-use std::ops::{Add, Mul, Sub};
+use std::ops::Mul;
 use style_traits::values::specified::AllowedNumericType;
 use std::fmt::{self, Write};
 use style_traits::{ParseError, SpecifiedValueInfo, StyleParseErrorKind, CssWriter, ToCss};
@@ -794,24 +794,6 @@ fn are_container_queries_enabled() -> bool {
     false
 }
 
-impl Sub<AbsoluteLength> for AbsoluteLength {
-    type Output = Self;
-
-    #[inline]
-    fn sub(self, rhs: Self) -> Self {
-        match (self, rhs) {
-            (AbsoluteLength::Px(x), AbsoluteLength::Px(y)) => AbsoluteLength::Px(x - y),
-            (AbsoluteLength::In(x), AbsoluteLength::In(y)) => AbsoluteLength::In(x - y),
-            (AbsoluteLength::Cm(x), AbsoluteLength::Cm(y)) => AbsoluteLength::Cm(x - y),
-            (AbsoluteLength::Mm(x), AbsoluteLength::Mm(y)) => AbsoluteLength::Mm(x - y),
-            (AbsoluteLength::Q(x), AbsoluteLength::Q(y)) => AbsoluteLength::Q(x - y),
-            (AbsoluteLength::Pt(x), AbsoluteLength::Pt(y)) => AbsoluteLength::Pt(x - y),
-            (AbsoluteLength::Pc(x), AbsoluteLength::Pc(y)) => AbsoluteLength::Pc(x - y),
-            _ => AbsoluteLength::Px(self.to_px() - rhs.to_px()),
-        }
-    }
-}
-
 /// A `<length>` without taking `calc` expressions into account
 ///
 /// <https://drafts.csswg.org/css-values/#lengths>