diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c6597fb8a16..5a1dcc5195cc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,10 +20,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Show suggestions for known `matchVariant` values ([#18798](https://github.com/tailwindlabs/tailwindcss/pull/18798))
 - Replace deprecated `clip` with `clip-path` in `sr-only` ([#18769](https://github.com/tailwindlabs/tailwindcss/pull/18769))
 - Hide internal fields from completions in `matchUtilities` ([#18820](https://github.com/tailwindlabs/tailwindcss/pull/18820))
+- Ignore `.vercel` folders by default (can be overridden by `@source …` rules) ([#18855](https://github.com/tailwindlabs/tailwindcss/pull/18855))
+- Consider variants starting with `@-` to be invalid (e.g. `@-2xl:flex`) ([#18869](https://github.com/tailwindlabs/tailwindcss/pull/18869))
 - Upgrade: Migrate `aria` theme keys to `@custom-variant` ([#18815](https://github.com/tailwindlabs/tailwindcss/pull/18815))
 - Upgrade: Migrate `data` theme keys to `@custom-variant` ([#18816](https://github.com/tailwindlabs/tailwindcss/pull/18816))
 - Upgrade: Migrate `supports` theme keys to `@custom-variant` ([#18817](https://github.com/tailwindlabs/tailwindcss/pull/18817))
-- Ignore `.vercel` folders by default (can be overridden by `@source …` rules) ([#18855](https://github.com/tailwindlabs/tailwindcss/pull/18855))
 
 ## [4.1.12] - 2025-08-13
 
diff --git a/packages/tailwindcss/src/candidate.ts b/packages/tailwindcss/src/candidate.ts
index c9bf85bf2d0e..d169ba758cc9 100644
--- a/packages/tailwindcss/src/candidate.ts
+++ b/packages/tailwindcss/src/candidate.ts
@@ -773,6 +773,11 @@ function* findRoots(input: string, exists: (input: string) => boolean): Iterable
       // can skip any further parsing.
       if (root[1] === '') break
 
+      // Edge case: `@-…` is not valid as a variant or a utility so we want to
+      // skip if an `@` is followed by a `-`. Otherwise `@-2xl:flex` and
+      // `@-2xl:flex` would be considered the same.
+      if (root[0] === '@' && exists('@') && input[idx] === '-') break
+
       yield root
     }
 
diff --git a/packages/tailwindcss/src/variants.test.ts b/packages/tailwindcss/src/variants.test.ts
index 016191dac0a7..f9d054a21656 100644
--- a/packages/tailwindcss/src/variants.test.ts
+++ b/packages/tailwindcss/src/variants.test.ts
@@ -2198,6 +2198,39 @@ test('container queries', async () => {
       }
     }"
   `)
+  expect(
+    await compileCss(
+      css`
+        @theme {
+          --container-lg: 1024px;
+          --container-foo-bar: 1440px;
+        }
+        @tailwind utilities;
+      `,
+      [
+        '@-lg:flex',
+        '@-lg/name:flex',
+        '@-[123px]:flex',
+        '@-[456px]/name:flex',
+        '@-foo-bar:flex',
+        '@-foo-bar/name:flex',
+
+        '@-min-lg:flex',
+        '@-min-lg/name:flex',
+        '@-min-[123px]:flex',
+        '@-min-[456px]/name:flex',
+        '@-min-foo-bar:flex',
+        '@-min-foo-bar/name:flex',
+
+        '@-max-lg:flex',
+        '@-max-lg/name:flex',
+        '@-max-[123px]:flex',
+        '@-max-[456px]/name:flex',
+        '@-max-foo-bar:flex',
+        '@-max-foo-bar/name:flex',
+      ],
+    ),
+  ).toEqual('')
 })
 
 test('variant order', async () => {