diff --git a/.claude/hooks/ui-kit-css-gate.sh b/.claude/hooks/ui-kit-css-gate.sh
new file mode 100755
index 000000000..e10b248ee
--- /dev/null
+++ b/.claude/hooks/ui-kit-css-gate.sh
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Blocks Claude Code Write/Edit/MultiEdit calls that would create or modify a
+# per-component .css file under a ui-kit package's src/, per the repo rule:
+# component styling goes through packages/uno-preset, .css is only for
+# tokens.css and theme/ sheets. Mirrors scripts/check-ui-kit-css.ts's
+# pattern/allowlist so the three enforcement layers (this hook, prek, CI)
+# agree on exactly one definition of "banned path".
+#
+# Same stdin JSON contract as turbo-filter-gate.sh: a PreToolUse hook reads
+# the tool call as JSON on stdin and blocks by exiting 2 with a stderr
+# message. Anything unparseable fails open.
+
+if ! command -v jq >/dev/null 2>&1; then
+  echo "ui-kit-css-gate: jq not on PATH, skipping check." >&2
+  exit 0
+fi
+
+INPUT="$(cat)"
+FILE_PATH="$(jq -r '.tool_input.file_path // empty' <<<"$INPUT" 2>/dev/null || true)"
+
+[ -n "$FILE_PATH" ] || exit 0
+
+NORMALIZED="$FILE_PATH"
+while printf '%s\n' "$NORMALIZED" | grep -Eq '(^|/)[^/]+/\.\.(/|$)|(^|/)\.(/|$)'; do
+  NORMALIZED="$(printf '%s\n' "$NORMALIZED" | sed -E 's#(^|/)[^/]+/\.\.(/|$)#\1#; s#(^|/)\.(/|$)#\1#; s#//#/#g')"
+done
+
+printf '%s\n' "$NORMALIZED" | grep -Eq '(^|/)packages/ui-kit-[^/]+/src/.*\.css$' || exit 0
+
+BASENAME="$(basename "$NORMALIZED")"
+if [ "$BASENAME" = "tokens.css" ]; then
+  exit 0
+fi
+if printf '%s\n' "$NORMALIZED" | grep -Eq '(^|/)theme/'; then
+  exit 0
+fi
+
+{
+  echo "ui-kit-css-gate: BLOCKED: $FILE_PATH is a banned per-component ui-kit .css file."
+  echo
+  echo "component styles belong in packages/uno-preset (keyframes -> src/animation.ts, animation"
+  echo "shortcuts -> src/motion.ts, effects/rules/preflights -> the preset), .css is only for"
+  echo "tokens/themes."
+} >&2
+
+exit 2
diff --git a/.claude/settings.json b/.claude/settings.json
index 3f5cf74db..3f34640b5 100644
--- a/.claude/settings.json
+++ b/.claude/settings.json
@@ -14,6 +14,15 @@
             "command": "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/turbo-filter-gate.sh"
           }
         ]
+      },
+      {
+        "matcher": "Write|Edit|MultiEdit",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/ui-kit-css-gate.sh"
+          }
+        ]
       }
     ]
   },
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ffc4ed634..297a7cd33 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -216,6 +216,9 @@ jobs:
         with:
           node-version: 22
           cache: pnpm
+      # ui-kit component styling goes through packages/uno-preset; per-component .css files
+      # are banned. Needs only node + git, so it runs before install/build.
+      - run: node scripts/check-ui-kit-css.ts
       - uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: .turbo
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index c590f919e..090076794 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -20,3 +20,9 @@ repos:
         pass_filenames: true
         files: '\.(m?[jt]sx?|c[jt]s)$'
         exclude: '^(.*/)?(dist|build|\.turbo)/'
+      - id: ui-kit-css-gate
+        name: ui-kit CSS gate (no per-component .css)
+        entry: node scripts/check-ui-kit-css.ts
+        language: system
+        pass_filenames: true
+        files: '^packages/ui-kit-[^/]+/src/.*\.css$'
diff --git a/AGENTS.md b/AGENTS.md
index af0bf6944..de1e62d9f 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -59,6 +59,9 @@ README.md; this file is the non-obvious operational rules.
 - TypeScript is strict (`noUncheckedIndexedAccess`, `verbatimModuleSyntax`, NodeNext). Avoid
   `any`/`as`/`@ts-ignore`.
 - oxfmt: no semicolons, single quotes, no bracket spacing, trailing commas, printWidth 120.
+- Component styles go through `packages/uno-preset` (`animation.ts` / `motion.ts` / effects /
+  preflights); `.css` files in ui-kit `src/` are banned except `tokens.css` and `theme/` sheets,
+  enforced by prek + CI + the agent PreToolUse hook.
 
 ## TanStack Router
 
diff --git a/scripts/check-ui-kit-css.ts b/scripts/check-ui-kit-css.ts
new file mode 100644
index 000000000..fe37a0196
--- /dev/null
+++ b/scripts/check-ui-kit-css.ts
@@ -0,0 +1,44 @@
+#!/usr/bin/env node
+import {execFileSync} from 'node:child_process'
+import {posix} from 'node:path'
+
+const UI_KIT_CSS_PATTERN = /^packages\/ui-kit-[^/]+\/src\/.*\.css$/
+const GIT_SCAN_PATHSPEC = ':(glob)packages/ui-kit-*/src/**/*.css'
+
+const MESSAGE =
+  'component styles belong in packages/uno-preset (keyframes -> src/animation.ts, animation ' +
+  'shortcuts -> src/motion.ts, effects/rules/preflights -> the preset), .css is only for ' +
+  'tokens/themes.'
+
+function isAllowlisted(path: string): boolean {
+  const segments = path.split('/')
+  const basename = segments[segments.length - 1]
+  if (basename === 'tokens.css') return true
+  return segments.includes('theme')
+}
+
+function findBannedPaths(paths: string[]): string[] {
+  return paths
+    .map((path) => posix.normalize(path.replaceAll('\\', '/')))
+    .filter((path) => UI_KIT_CSS_PATTERN.test(path) && !isAllowlisted(path))
+}
+
+function scanTrackedFiles(): string[] {
+  const output = execFileSync('git', ['ls-files', GIT_SCAN_PATHSPEC], {encoding: 'utf8'})
+  return output.split('\n').filter((line) => line.length > 0)
+}
+
+function main(): void {
+  const argPaths = process.argv.slice(2)
+  const candidatePaths = argPaths.length > 0 ? argPaths : scanTrackedFiles()
+  const banned = findBannedPaths(candidatePaths)
+
+  if (banned.length === 0) return
+
+  console.error('check-ui-kit-css: banned ui-kit component .css file(s) found:\n')
+  for (const path of banned) console.error(`  ${path}`)
+  console.error(`\n${MESSAGE}`)
+  process.exitCode = 1
+}
+
+main()