diff --git a/packages/rrweb-snapshot/src/css.ts b/packages/rrweb-snapshot/src/css.ts
index edeb3470b5..4645deae4f 100644
--- a/packages/rrweb-snapshot/src/css.ts
+++ b/packages/rrweb-snapshot/src/css.ts
@@ -56,9 +56,9 @@ export interface Node {
   };
 }
 
-export interface NodeWithOptionalRules extends Node {
+export interface NodeWithRules extends Node {
   /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules?: Array<Rule | Comment | AtRule>;
+  rules: Array<Rule | Comment | AtRule>;
 }
 
 export interface Rule extends Node {
@@ -103,7 +103,7 @@ export interface CustomMedia extends Node {
 /**
  * The @document at-rule.
  */
-export interface Document extends NodeWithOptionalRules {
+export interface Document extends NodeWithRules {
   /** The part following @document. */
   document?: string;
   /** The vendor prefix in @document, or undefined if there is none. */
@@ -121,7 +121,7 @@ export interface FontFace extends Node {
 /**
  * The @host at-rule.
  */
-export type Host = NodeWithOptionalRules;
+export type Host = NodeWithRules;
 
 /**
  * The @import at-rule.
@@ -153,7 +153,7 @@ export interface KeyFrame extends Node {
 /**
  * The @media at-rule.
  */
-export interface Media extends NodeWithOptionalRules {
+export interface Media extends NodeWithRules {
   /** The part following @media. */
   media?: string;
 }
@@ -179,7 +179,7 @@ export interface Page extends Node {
 /**
  * The @supports at-rule.
  */
-export interface Supports extends NodeWithOptionalRules {
+export interface Supports extends NodeWithRules {
   /** The part following @supports. */
   supports?: string;
 }
@@ -201,10 +201,8 @@ export type AtRule =
 /**
  * A collection of rules
  */
-export interface StyleRules {
+export interface StyleRules extends NodeWithRules {
   source?: string;
-  /** Array of nodes with the types rule, comment and any of the at-rule types. */
-  rules: Array<Rule | Comment | AtRule>;
   /** Array of Errors. Errors collected during parsing when option silent is true. */
   parsingErrors?: ParserError[];
 }
diff --git a/packages/rrweb-snapshot/src/rebuild.ts b/packages/rrweb-snapshot/src/rebuild.ts
index 9ccce1d8f9..6531cfe339 100644
--- a/packages/rrweb-snapshot/src/rebuild.ts
+++ b/packages/rrweb-snapshot/src/rebuild.ts
@@ -1,4 +1,4 @@
-import { StyleRules, Rule, Media, NodeWithOptionalRules, parse } from './css';
+import { Rule, Media, NodeWithRules, parse } from './css';
 import {
   serializedNodeWithId,
   NodeType,
@@ -81,9 +81,7 @@ export function adaptCssForReplay(cssText: string, cache: BuildCache): string {
 
   const selectors: string[] = [];
   const medias: string[] = [];
-  function getSelectors(
-    rule: StyleRules | Rule | Media | NodeWithOptionalRules,
-  ) {
+  function getSelectors(rule: Rule | Media | NodeWithRules) {
     if ('selectors' in rule && rule.selectors) {
       rule.selectors.forEach((selector: string) => {
         if (HOVER_SELECTOR.test(selector)) {