diff --git a/types/cssom/index.d.ts b/types/cssom/index.d.ts
new file mode 100644
index 0000000000..50b2357c32
--- /dev/null
+++ b/types/cssom/index.d.ts
@@ -0,0 +1,174 @@
+// Type definitions for cssom 0.4
+// Project: https://github.com/NV/CSSOM#readme
+// Definitions by: ExE Boss <https://github.com/ExE-Boss>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+export as namespace CSSOM;
+
+/**
+ * Produces a deep copy of stylesheet — the instance variables of stylesheet are copied recursively.
+ */
+export function clone(stylesheet: CSSStyleSheet): CSSStyleSheet;
+
+export function parse(token: string): CSSStyleSheet;
+
+export abstract class StyleSheet {
+	parentStyleSheet: StyleSheet | null;
+}
+
+export class CSSStyleSheet extends StyleSheet {
+	cssRules: CSSRule[];
+
+	deleteRule(index: number): void;
+	insertRule(rule: string, index?: number): number;
+}
+
+export abstract class CSSRule {
+	readonly cssText: string;
+
+	parentRule: CSSRule | null;
+	parentStyleSheet: StyleSheet | null;
+
+	readonly type: number;
+}
+
+export namespace CSSRule {
+	/** @deprecated Obsolete */
+	const UNKNOWN_RULE = 0;
+	const STYLE_RULE = 1;
+	/** @deprecated Obsolete */
+	const CHARSET_RULE = 2;
+	const IMPORT_RULE = 3;
+	const MEDIA_RULE = 4;
+	const FONT_FACE_RULE = 5;
+	const PAGE_RULE = 6;
+	const KEYFRAMES_RULE = 7;
+	const KEYFRAME_RULE = 8;
+	const MARGIN_RULE = 9;
+	const NAMESPACE_RULE = 10;
+	const COUNTER_STYLE_RULE = 11;
+	const SUPPORTS_RULE = 12;
+	const DOCUMENT_RULE = 13;
+	const FONT_FEATURE_VALUES_RULE = 14;
+	const VIEWPORT_RULE = 15;
+	const REGION_STYLE_RULE = 16;
+}
+
+export class CSSStyleRule extends CSSRule {
+	cssText: string;
+
+	selectorText: string;
+	style: CSSStyleDeclaration;
+
+	static parse(ruleText: any): any;
+	readonly type: 1;
+}
+
+export class CSSImportRule extends CSSRule {
+	cssText: string;
+
+	href: string;
+	media: MediaList;
+	styleSheet: CSSStyleSheet;
+
+	readonly type: 3;
+}
+
+export class CSSMediaRule extends CSSRule {
+	media: MediaList;
+	cssRules: CSSRule[];
+
+	readonly type: 4;
+}
+
+export class CSSFontFaceRule extends CSSRule {
+	style: CSSStyleDeclaration;
+
+	readonly type: 5;
+}
+
+export class CSSKeyframesRule extends CSSRule {
+	name: string;
+	cssRules: CSSRule[];
+
+	readonly type: 7;
+}
+
+export class CSSKeyframeRule extends CSSRule {
+	keyText: string;
+	style: CSSStyleDeclaration;
+
+	readonly type: 8;
+}
+
+export class CSSSupportsRule extends CSSRule {
+	conditionText: string;
+	cssRules: CSSRule[];
+
+	readonly type: 12;
+}
+
+/** @deprecated Removed from spec */
+export class CSSDocumentRule extends CSSRule {
+	matcher: MatcherList;
+	cssRules: CSSRule[];
+
+	readonly type: 13;
+}
+
+/**
+ * @deprecated Legacy Shadow DOM v0
+ * @see https://www.w3.org/TR/2013/WD-shadow-dom-20130514/#host-at-rule
+ */
+export class CSSHostRule extends CSSRule {
+	cssRules: CSSRule[];
+
+	readonly type: 1001;
+}
+
+export class CSSStyleDeclaration {
+	cssText: string;
+	length: number;
+	parentRule: CSSRule | null;
+
+	getPropertyPriority(name: string): string;
+	getPropertyValue(name: string): string;
+	removeProperty(name: string): string;
+	setProperty(name: string, value: string | null, priority?: string | null): void;
+
+	[index: number]: string;
+}
+
+/** @deprecated */
+export class CSSValue {
+	/** @unsupported The getter and setter are currently unimplemented and throw unconditionally. */
+	cssText: string;
+}
+
+/** @deprecated */
+export class CSSValueExpression extends CSSValue {
+	constructor(token: string, idx: number);
+
+	parse(): { error: any } | { idx: number; expression: string };
+}
+
+/** @deprecated Removed from spec */
+export class MatcherList {
+	length: number;
+	matcherText: string;
+
+	appendMatcher(matcher: string): void;
+	deleteMatcher(matcher: string): void;
+
+	[index: number]: string;
+}
+
+export class MediaList {
+	length: number;
+	mediaText: string;
+
+	appendMedium(medium: string): void;
+	deleteMedium(medium: string): void;
+
+	[index: number]: string;
+}
diff --git a/types/cssom/test/cssom.cjs.test.ts b/types/cssom/test/cssom.cjs.test.ts
new file mode 100644
index 0000000000..2c97a060fd
--- /dev/null
+++ b/types/cssom/test/cssom.cjs.test.ts
@@ -0,0 +1,17 @@
+import * as CSSOM from 'cssom';
+
+let styleSheet: CSSOM.CSSStyleSheet;
+
+styleSheet = CSSOM.parse(`
+@import url("./foo.css");
+
+*,
+::before,
+::after,
+::marker {
+	box-sizing: border-box;
+}
+`);
+
+styleSheet.parentStyleSheet; // $ExpectType StyleSheet | null
+styleSheet.cssRules; // $ExpectType CSSRule[]
diff --git a/types/cssom/test/cssom.umd.test.ts b/types/cssom/test/cssom.umd.test.ts
new file mode 100644
index 0000000000..c61289a724
--- /dev/null
+++ b/types/cssom/test/cssom.umd.test.ts
@@ -0,0 +1,17 @@
+/// <reference types="cssom"/>
+
+let styleSheet: CSSOM.CSSStyleSheet;
+
+styleSheet = CSSOM.parse(`
+@import url("./foo.css");
+
+*,
+::before,
+::after,
+::marker {
+	box-sizing: border-box;
+}
+`);
+
+styleSheet.parentStyleSheet; // $ExpectType StyleSheet | null
+styleSheet.cssRules; // $ExpectType CSSRule[]
diff --git a/types/cssom/tsconfig.json b/types/cssom/tsconfig.json
new file mode 100644
index 0000000000..d466217096
--- /dev/null
+++ b/types/cssom/tsconfig.json
@@ -0,0 +1,20 @@
+{
+	"compilerOptions": {
+		"module": "commonjs",
+		"lib": ["ES2015"],
+		"noImplicitAny": true,
+		"noImplicitThis": true,
+		"strictFunctionTypes": true,
+		"strictNullChecks": true,
+		"baseUrl": "../",
+		"typeRoots": ["../"],
+		"types": [],
+		"noEmit": true,
+		"forceConsistentCasingInFileNames": true
+	},
+	"files": [
+		"test/cssom.cjs.test.ts",
+		"test/cssom.umd.test.ts",
+		"index.d.ts"
+	]
+}
diff --git a/types/cssom/tslint.json b/types/cssom/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/cssom/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }