diff --git a/.gitignore b/.gitignore
index c32bc99..722fe85 100644
--- a/.gitignore
+++ b/.gitignore
@@ -52,6 +52,10 @@ next-env.d.ts
 !.cursor/rules/
 !.cursor/skills
 
+# sparkle-design-internal をワークスペース内に置いた場合（スキルは .cursor/skills に同期）
+# en: Local clone of internal repo at repo root — avoid accidental commits
+/sparkle-design-internal/
+
 # vscode
 # .vscode
 
diff --git a/package.json b/package.json
index 4322518..056e2df 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,6 @@
     "build:registry:merge": "node scripts/merge-registry.mjs",
     "build:registry:vercel": "bash scripts/build-registry-vercel.sh",
     "preinstall": "npx only-allow pnpm",
-    "postinstall": "npx lightningcss --version || true",
     "build:package": "rm -rf dist && tsc -p tsconfig.build.json && tsc-alias -p tsconfig.build.json",
     "format": "prettier --config ./.prettierrc -w \"**/*.{js,ts,tsx,css,md,json}\"",
     "format:check": "prettier --config ./.prettierrc --check \"**/*.{js,ts,tsx,css,md,json}\"",
diff --git a/src/app/globals.css b/src/app/globals.css
index 7a5c3ba..a997b81 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -126,6 +126,61 @@
     height: 0;
   }
 }
+
+@keyframes sparkle-overlay-in {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}
+@keyframes sparkle-overlay-out {
+  from {
+    opacity: 1;
+  }
+  to {
+    opacity: 0;
+  }
+}
+
+@keyframes sparkle-modal-in {
+  from {
+    opacity: 0;
+    transform: translateY(8px) scale(0.98);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0px) scale(1);
+  }
+}
+@keyframes sparkle-modal-out {
+  from {
+    opacity: 1;
+    transform: translateY(0px) scale(1);
+  }
+  to {
+    opacity: 0;
+    transform: translateY(6px) scale(0.98);
+  }
+}
+
+@keyframes sparkle-fade-in {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}
+@keyframes sparkle-fade-out {
+  from {
+    opacity: 1;
+  }
+  to {
+    opacity: 0;
+  }
+}
 @utility accordion-down {
   animation: accordion-down 0.2s ease-out;
 }
diff --git a/src/components/ui/link/index.stories.tsx b/src/components/ui/link/index.stories.tsx
index f27d460..6300dc7 100644
--- a/src/components/ui/link/index.stories.tsx
+++ b/src/components/ui/link/index.stories.tsx
@@ -1,4 +1,5 @@
 import type { Meta, StoryObj } from "@storybook/react";
+import NextLink from "next/link";
 import React from "react";
 import { Link } from "./index";
 
@@ -26,7 +27,7 @@ export const Default: Story = {
   args: {
     children: "リンクテキスト",
     isOpenInNew: false,
-    href: "#",
+    href: "/",
   },
 };
 
@@ -34,7 +35,7 @@ export const ExternalLink: Story = {
   args: {
     children: "リンクテキスト",
     isOpenInNew: true,
-    href: "#",
+    href: "https://example.com",
   },
 };
 
@@ -45,7 +46,7 @@ export const ExternalLink: Story = {
 export const AsChild: Story = {
   render: () => (
     <Link asChild>
-      <a href="#">next/link 等に置き換え可能</a>
+      <NextLink href="/">next/link 等に置き換え可能</NextLink>
     </Link>
   ),
 };
@@ -71,6 +72,6 @@ export const CustomTypography: Story = {
   args: {
     children: "カスタムタイポグラフィ",
     className: "character-4-bold-pro",
-    href: "#",
+    href: "/",
   },
 };
diff --git a/src/components/ui/modal/index.stories.tsx b/src/components/ui/modal/index.stories.tsx
index fb60b22..6132778 100644
--- a/src/components/ui/modal/index.stories.tsx
+++ b/src/components/ui/modal/index.stories.tsx
@@ -234,3 +234,55 @@ export const EnabledOverlayClickToClose: Story = {
     );
   },
 };
+
+/**
+ * 開閉モーション（オーバーレイフェード＋パネル fade／zoom）の確認用。
+ * en: For verifying open/close motion (overlay fade + panel fade/zoom).
+ */
+export const MotionPreview: Story = {
+  parameters: {
+    layout: "fullscreen",
+    docs: {
+      description: {
+        story:
+          "全画面レイアウトでスクリムとパネルの動きを確認する。**開く**：トリガーボタン。**閉じる**：×／キャンセル／保存／Esc。オーバーレイクリックは既定で閉じない（仕様確認用）。オーバーレイはフェード（Open 180ms / Close 160ms）、コンテンツは opacity + translateY + scale（Open 240ms / delay 20ms、Close 200ms）で出入りする。\n\nen: Use fullscreen to judge scrim and panel motion. Trigger opens; close via ×, footer buttons, or Esc. Overlay fades (open 180ms, close 160ms). Content enters/leaves with opacity + translateY + scale (open 240ms with 20ms delay, close 200ms).",
+      },
+    },
+  },
+  render: () => {
+    const [open, setOpen] = useState(false);
+    return (
+      <div className="flex min-h-screen items-center justify-center p-8">
+        <Modal open={open} onOpenChange={setOpen}>
+          <ModalTrigger asChild>
+            <Button>モーダルを開く（モーション確認）</Button>
+          </ModalTrigger>
+          <ModalContent>
+            <ModalHeader>
+              <ModalTitle>モーション確認</ModalTitle>
+              <ModalClose />
+            </ModalHeader>
+            <ModalBody>
+              <p className="text-pretty">
+                開閉を繰り返して、オーバーレイのフェードとパネルのスケール／不透明度の同期を確認してください。
+              </p>
+            </ModalBody>
+            <ModalFooter>
+              <Button
+                size="sm"
+                theme="neutral"
+                variant="ghost"
+                onClick={() => setOpen(false)}
+              >
+                キャンセル
+              </Button>
+              <Button size="sm" onClick={() => setOpen(false)}>
+                保存
+              </Button>
+            </ModalFooter>
+          </ModalContent>
+        </Modal>
+      </div>
+    );
+  },
+};
diff --git a/src/components/ui/modal/index.tsx b/src/components/ui/modal/index.tsx
index e0024e7..ac27870 100644
--- a/src/components/ui/modal/index.tsx
+++ b/src/components/ui/modal/index.tsx
@@ -127,7 +127,13 @@ function ModalOverlay({
     <DialogPrimitive.Overlay
       data-slot="modal-overlay"
       className={cn(
-        "data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 fixed inset-0 z-50 bg-black/50",
+        [
+          "fixed inset-0 z-50 bg-black/50",
+          "data-[state=open]:animate-[sparkle-overlay-in_180ms_ease-out_0ms_both]",
+          "data-[state=closed]:animate-[sparkle-overlay-out_160ms_ease-in_0ms_both]",
+          "motion-reduce:data-[state=open]:animate-[sparkle-fade-in_120ms_ease-out_0ms_both]",
+          "motion-reduce:data-[state=closed]:animate-[sparkle-fade-out_120ms_ease-in_0ms_both]",
+        ].join(" "),
         className
       )}
       {...props}
@@ -199,18 +205,31 @@ function ModalContent({
   return (
     <ModalPortal data-slot="modal-portal">
       <ModalOverlay />
-      <DialogPrimitive.Content
-        data-slot="modal-content"
-        className={cn(
-          sizeClass,
-          "z-50 flex flex-col gap-0 w-full max-h-[calc(100vh-80px)] bg-white border-divider-low py-4 rounded-modal data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 fixed top-[50%] left-[50%] translate-x-[-50%] translate-y-[-50%] shadow-lg duration-200",
-          className
-        )}
-        onInteractOutside={handleInteractOutside}
-        {...props}
+      <div
+        data-slot="modal-positioner"
+        className="fixed inset-0 z-50 flex items-center justify-center p-10 pointer-events-none"
       >
-        {children}
-      </DialogPrimitive.Content>
+        <DialogPrimitive.Content
+          data-slot="modal-content"
+          className={cn(
+            sizeClass,
+            [
+              "pointer-events-auto",
+              "flex flex-col gap-0 w-full max-h-[calc(100vh-80px)]",
+              "bg-white border-divider-low py-4 rounded-modal shadow-lg",
+              "data-[state=open]:animate-[sparkle-modal-in_240ms_cubic-bezier(0.16,1,0.3,1)_20ms_both]",
+              "data-[state=closed]:animate-[sparkle-modal-out_200ms_cubic-bezier(0.32,0,0.67,0)_0ms_both]",
+              "motion-reduce:data-[state=open]:animate-[sparkle-fade-in_120ms_ease-out_0ms_both]",
+              "motion-reduce:data-[state=closed]:animate-[sparkle-fade-out_120ms_ease-in_0ms_both]",
+            ].join(" "),
+            className
+          )}
+          onInteractOutside={handleInteractOutside}
+          {...props}
+        >
+          {children}
+        </DialogPrimitive.Content>
+      </div>
     </ModalPortal>
   );
 }