diff --git a/components/style/cascade_info.rs b/components/style/cascade_info.rs
index d0c584e7e0f..5c7565909db 100644
--- a/components/style/cascade_info.rs
+++ b/components/style/cascade_info.rs
@@ -1,6 +1,11 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! A structure to collect information about the cascade.
+
+#![deny(missing_docs)]
+
 use dom::TNode;
 use properties::{DeclaredValue, PropertyDeclaration};
 use values::HasViewportPercentage;
@@ -12,12 +17,17 @@ use values::HasViewportPercentage;
 /// non-inherited property is explicitly inherited, in order to cut-off the
 /// traversal.
 pub struct CascadeInfo {
+    /// Whether we've seen viewport units so far.
     pub saw_viewport_units: bool,
+    /// Whether the cascade has been marked as finished. This is a debug-only
+    /// flag to ensure `finish` is called, given it's optional to not pass a
+    /// `CascadeInfo`.
     #[cfg(debug_assertions)]
     finished: bool,
 }
 
 impl CascadeInfo {
+    /// Construct a new `CascadeInfo`.
     #[cfg(debug_assertions)]
     pub fn new() -> Self {
         CascadeInfo {
@@ -26,6 +36,7 @@ impl CascadeInfo {
         }
     }
 
+    /// Construct a new `CascadeInfo`.
     #[cfg(not(debug_assertions))]
     pub fn new() -> Self {
         CascadeInfo {
@@ -40,7 +51,7 @@ impl CascadeInfo {
     pub fn on_cascade_property<T>(&mut self,
                                   _property_declaration: &PropertyDeclaration,
                                   value: &DeclaredValue<T>)
-        where T: HasViewportPercentage
+        where T: HasViewportPercentage,
     {
         // TODO: we can be smarter and keep a property bitfield to keep track of
         // the last applying rule.
@@ -57,6 +68,11 @@ impl CascadeInfo {
     #[cfg(not(debug_assertions))]
     fn mark_as_finished_if_appropriate(&mut self) {}
 
+    /// Called when the cascade is finished, in order to use the information
+    /// we've collected.
+    ///
+    /// Currently used for styling to mark a node as needing restyling when the
+    /// viewport size changes.
     #[allow(unsafe_code)]
     pub fn finish<N: TNode>(mut self, node: &N) {
         self.mark_as_finished_if_appropriate();
@@ -73,6 +89,7 @@ impl CascadeInfo {
 impl Drop for CascadeInfo {
     fn drop(&mut self) {
         debug_assert!(self.finished,
-                      "Didn't use the result of CascadeInfo, if you don't need it, consider passing None");
+                      "Didn't use the result of CascadeInfo, if you don't need \
+                      it, consider passing None");
     }
 }