From c6e308a56eac824db461cce045fce3cc94e4788a Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Wed, 21 Oct 2026 11:41:57 +0000
Subject: [PATCH 1/3] feat: parse nested feature-value blocks inside
 @font-feature-values

---
 src/parse.test.ts | 17 +++++++++++++++++
 src/parse.ts      |  7 ++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/parse.test.ts b/src/parse.test.ts
index c67247d..04c9d6d 100644
--- a/src/parse.test.ts
+++ b/src/parse.test.ts
@@ -885,6 +885,23 @@ describe('Core Nodes', () => {
 					expect(decl2.type).toBe(DECLARATION)
 				})
 
+				test('@font-feature-values with nested at-rules', () => {
+					const root = parse(
+						'@font-feature-values Font One { @styleset { nice-style: 12; } @swash { fancy: 1 } } a {}',
+					)
+					const rule = root.first_child! as Atrule
+					expect(rule.name).toBe('font-feature-values')
+					expect(rule.next_sibling!.type).toBe(STYLE_RULE)
+					expect(rule.next_sibling!.next_sibling).toBeNull()
+
+					const [styleset, swash] = rule.block!.children
+					expect(styleset.type).toBe(AT_RULE)
+					expect((styleset as Atrule).name).toBe('styleset')
+					expect(styleset.block!.first_child!.type).toBe(DECLARATION)
+					expect((swash as Atrule).name).toBe('swash')
+					expect(swash.block!.first_child!.type).toBe(DECLARATION)
+				})
+
 				test('@page', () => {
 					const source = '@page { margin: 1in; }'
 					const root = parse(source)
diff --git a/src/parse.ts b/src/parse.ts
index d7a0a16..90d4201 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -57,7 +57,12 @@ export interface ParserOptions {
 // Static at-rule lookup sets for fast classification
 const DECLARATION_AT_RULES = new Set([
 	'font-face',
-	'font-feature-values',
+	'styleset',
+	'stylistic',
+	'character-variant',
+	'swash',
+	'ornaments',
+	'annotation',
 	'page',
 	'property',
 	'counter-style',

From fb3a42b368f4768ff22b8f07e4a5cb788ef55b71 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Wed, 21 Oct 2026 11:44:36 +0000
Subject: [PATCH 2/3] feat: parse nested margin at-rules inside @page

---
 src/parse.test.ts | 16 ++++++++++++++++
 src/parse.ts      | 17 ++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/parse.test.ts b/src/parse.test.ts
index 04c9d6d..1a2e7f5 100644
--- a/src/parse.test.ts
+++ b/src/parse.test.ts
@@ -902,6 +902,22 @@ describe('Core Nodes', () => {
 					expect(swash.block!.first_child!.type).toBe(DECLARATION)
 				})
 
+				test('@page with nested margin at-rules', () => {
+					const root = parse(
+						'@page :first { margin: 1in; @top-left { content: "a"; } @bottom-right-corner { color: red } } a {}',
+					)
+					const page = root.first_child! as Atrule
+					expect(page.name).toBe('page')
+					expect(page.next_sibling!.type).toBe(STYLE_RULE)
+
+					const [margin, top_left, bottom_right] = page.block!.children
+					expect(margin.type).toBe(DECLARATION)
+					expect((top_left as Atrule).name).toBe('top-left')
+					expect(top_left.block!.first_child!.type).toBe(DECLARATION)
+					expect((bottom_right as Atrule).name).toBe('bottom-right-corner')
+					expect(bottom_right.block!.first_child!.type).toBe(DECLARATION)
+				})
+
 				test('@page', () => {
 					const source = '@page { margin: 1in; }'
 					const root = parse(source)
diff --git a/src/parse.ts b/src/parse.ts
index 90d4201..1a45ac6 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -63,7 +63,22 @@ const DECLARATION_AT_RULES = new Set([
 	'swash',
 	'ornaments',
 	'annotation',
-	'page',
+	'top-left-corner',
+	'top-left',
+	'top-center',
+	'top-right',
+	'top-right-corner',
+	'bottom-left-corner',
+	'bottom-left',
+	'bottom-center',
+	'bottom-right',
+	'bottom-right-corner',
+	'left-top',
+	'left-middle',
+	'left-bottom',
+	'right-top',
+	'right-middle',
+	'right-bottom',
 	'property',
 	'counter-style',
 	'color-profile',

From 58772c010cb9e17813bc99dec2f2aa22e5d8441e Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Wed, 21 Oct 2026 11:59:49 +0000
Subject: [PATCH 3/3] fix: type errors in nested at-rule tests

---
 src/parse.test.ts | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/parse.test.ts b/src/parse.test.ts
index 1a2e7f5..f6eb5b7 100644
--- a/src/parse.test.ts
+++ b/src/parse.test.ts
@@ -894,11 +894,11 @@ describe('Core Nodes', () => {
 					expect(rule.next_sibling!.type).toBe(STYLE_RULE)
 					expect(rule.next_sibling!.next_sibling).toBeNull()
 
-					const [styleset, swash] = rule.block!.children
+					const [styleset, swash] = rule.block!.children as Atrule[]
 					expect(styleset.type).toBe(AT_RULE)
-					expect((styleset as Atrule).name).toBe('styleset')
+					expect(styleset.name).toBe('styleset')
 					expect(styleset.block!.first_child!.type).toBe(DECLARATION)
-					expect((swash as Atrule).name).toBe('swash')
+					expect(swash.name).toBe('swash')
 					expect(swash.block!.first_child!.type).toBe(DECLARATION)
 				})
 
@@ -910,11 +910,11 @@ describe('Core Nodes', () => {
 					expect(page.name).toBe('page')
 					expect(page.next_sibling!.type).toBe(STYLE_RULE)
 
-					const [margin, top_left, bottom_right] = page.block!.children
+					const [margin, top_left, bottom_right] = page.block!.children as Atrule[]
 					expect(margin.type).toBe(DECLARATION)
-					expect((top_left as Atrule).name).toBe('top-left')
+					expect(top_left.name).toBe('top-left')
 					expect(top_left.block!.first_child!.type).toBe(DECLARATION)
-					expect((bottom_right as Atrule).name).toBe('bottom-right-corner')
+					expect(bottom_right.name).toBe('bottom-right-corner')
 					expect(bottom_right.block!.first_child!.type).toBe(DECLARATION)
 				})