diff --git a/packages/tailwindcss-language-server/tests/diagnostics/css-conflict/vue-style-lang-sass.json b/packages/tailwindcss-language-server/tests/diagnostics/css-conflict/vue-style-lang-sass.json
new file mode 100644
index 00000000..7e9da86b
--- /dev/null
+++ b/packages/tailwindcss-language-server/tests/diagnostics/css-conflict/vue-style-lang-sass.json
@@ -0,0 +1,116 @@
+{
+  "code": "<style lang=\"sass\">\n.foo\n  @apply uppercase lowercase\n</style>",
+  "language": "vue",
+  "expected": [
+    {
+      "code": "cssConflict",
+      "className": {
+        "className": "uppercase",
+        "classList": {
+          "classList": "uppercase lowercase",
+          "range": {
+            "start": { "line": 2, "character": 9 },
+            "end": { "line": 2, "character": 28 }
+          },
+          "important": false
+        },
+        "relativeRange": {
+          "start": { "line": 0, "character": 0 },
+          "end": { "line": 0, "character": 9 }
+        },
+        "range": { "start": { "line": 2, "character": 9 }, "end": { "line": 2, "character": 18 } }
+      },
+      "otherClassNames": [
+        {
+          "className": "lowercase",
+          "classList": {
+            "classList": "uppercase lowercase",
+            "range": {
+              "start": { "line": 2, "character": 9 },
+              "end": { "line": 2, "character": 28 }
+            },
+            "important": false
+          },
+          "relativeRange": {
+            "start": { "line": 0, "character": 10 },
+            "end": { "line": 0, "character": 19 }
+          },
+          "range": {
+            "start": { "line": 2, "character": 19 },
+            "end": { "line": 2, "character": 28 }
+          }
+        }
+      ],
+      "range": { "start": { "line": 2, "character": 9 }, "end": { "line": 2, "character": 18 } },
+      "severity": 2,
+      "message": "'uppercase' applies the same CSS properties as 'lowercase'.",
+      "relatedInformation": [
+        {
+          "message": "lowercase",
+          "location": {
+            "uri": "{{URI}}",
+            "range": {
+              "start": { "line": 2, "character": 19 },
+              "end": { "line": 2, "character": 28 }
+            }
+          }
+        }
+      ]
+    },
+    {
+      "code": "cssConflict",
+      "className": {
+        "className": "lowercase",
+        "classList": {
+          "classList": "uppercase lowercase",
+          "range": {
+            "start": { "line": 2, "character": 9 },
+            "end": { "line": 2, "character": 28 }
+          },
+          "important": false
+        },
+        "relativeRange": {
+          "start": { "line": 0, "character": 10 },
+          "end": { "line": 0, "character": 19 }
+        },
+        "range": { "start": { "line": 2, "character": 19 }, "end": { "line": 2, "character": 28 } }
+      },
+      "otherClassNames": [
+        {
+          "className": "uppercase",
+          "classList": {
+            "classList": "uppercase lowercase",
+            "range": {
+              "start": { "line": 2, "character": 9 },
+              "end": { "line": 2, "character": 28 }
+            },
+            "important": false
+          },
+          "relativeRange": {
+            "start": { "line": 0, "character": 0 },
+            "end": { "line": 0, "character": 9 }
+          },
+          "range": {
+            "start": { "line": 2, "character": 9 },
+            "end": { "line": 2, "character": 18 }
+          }
+        }
+      ],
+      "range": { "start": { "line": 2, "character": 19 }, "end": { "line": 2, "character": 28 } },
+      "severity": 2,
+      "message": "'lowercase' applies the same CSS properties as 'uppercase'.",
+      "relatedInformation": [
+        {
+          "message": "uppercase",
+          "location": {
+            "uri": "{{URI}}",
+            "range": {
+              "start": { "line": 2, "character": 9 },
+              "end": { "line": 2, "character": 18 }
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
diff --git a/packages/tailwindcss-language-server/tests/diagnostics/diagnostics.test.js b/packages/tailwindcss-language-server/tests/diagnostics/diagnostics.test.js
index 4da6946d..4a37ee2d 100644
--- a/packages/tailwindcss-language-server/tests/diagnostics/diagnostics.test.js
+++ b/packages/tailwindcss-language-server/tests/diagnostics/diagnostics.test.js
@@ -32,6 +32,7 @@ withFixture('basic', (c) => {
   testFixture('css-conflict/css')
   testFixture('css-conflict/css-multi-rule')
   testFixture('css-conflict/css-multi-prop')
+  testFixture('css-conflict/vue-style-lang-sass')
   testFixture('invalid-screen/simple')
   testFixture('invalid-theme/simple')
 })
@@ -63,6 +64,7 @@ withFixture('v4/basic', (c) => {
   testFixture('css-conflict/variants-positive')
   testFixture('css-conflict/jsx-concat-negative')
   testFixture('css-conflict/jsx-concat-positive')
+  testFixture('css-conflict/vue-style-lang-sass')
   // testFixture('css-conflict/css')
   // testFixture('css-conflict/css-multi-rule')
   // testFixture('css-conflict/css-multi-prop')
diff --git a/packages/tailwindcss-language-server/tests/hover/hover.test.js b/packages/tailwindcss-language-server/tests/hover/hover.test.js
index 544ea1e3..f1b847c3 100644
--- a/packages/tailwindcss-language-server/tests/hover/hover.test.js
+++ b/packages/tailwindcss-language-server/tests/hover/hover.test.js
@@ -75,6 +75,20 @@ withFixture('basic', (c) => {
       end: { line: 0, character: 31 },
     },
   })
+
+  testHover('vue <style lang=sass>', {
+    lang: 'vue',
+    text: `<style lang="sass">
+.foo
+  @apply underline
+</style>`,
+    position: { line: 2, character: 13 },
+    expected: '.underline {\n' + '  text-decoration-line: underline;\n' + '}',
+    expectedRange: {
+      start: { line: 2, character: 9 },
+      end: { line: 2, character: 18 },
+    },
+  })
 })
 
 withFixture('v4/basic', (c) => {
@@ -148,4 +162,18 @@ withFixture('v4/basic', (c) => {
       end: { line: 0, character: 31 },
     },
   })
+
+  testHover('vue <style lang=sass>', {
+    lang: 'vue',
+    text: `<style lang="sass">
+.foo
+  @apply underline
+</style>`,
+    position: { line: 2, character: 13 },
+    expected: '.underline {\n' + '  text-decoration-line: underline;\n' + '}',
+    expectedRange: {
+      start: { line: 2, character: 9 },
+      end: { line: 2, character: 18 },
+    },
+  })
 })
diff --git a/packages/tailwindcss-language-service/src/util/css.ts b/packages/tailwindcss-language-service/src/util/css.ts
index 14950397..079e4221 100644
--- a/packages/tailwindcss-language-service/src/util/css.ts
+++ b/packages/tailwindcss-language-service/src/util/css.ts
@@ -6,12 +6,21 @@ import type { State } from './state'
 import { cssLanguages } from './languages'
 import { getLanguageBoundaries } from './getLanguageBoundaries'
 
-export function isCssDoc(state: State, doc: TextDocument): boolean {
-  const userCssLanguages = Object.keys(state.editor.userLanguages).filter((lang) =>
-    cssLanguages.includes(state.editor.userLanguages[lang]),
-  )
+function getCssLanguages(state: State) {
+  const userCssLanguages = Object
+    .keys(state.editor.userLanguages)
+    .filter((lang) => cssLanguages.includes(state.editor.userLanguages[lang]))
+
+  return [...cssLanguages, ...userCssLanguages]
+}
 
-  return [...cssLanguages, ...userCssLanguages].indexOf(doc.languageId) !== -1
+export function isCssLanguage(state: State, lang: string) {
+  return getCssLanguages(state).indexOf(lang) !== -1
+}
+
+
+export function isCssDoc(state: State, doc: TextDocument): boolean {
+  return isCssLanguage(state, doc.languageId)
 }
 
 export function isCssContext(state: State, doc: TextDocument, position: Position): boolean {
diff --git a/packages/tailwindcss-language-service/src/util/find.ts b/packages/tailwindcss-language-service/src/util/find.ts
index 94fae47d..fead1bd7 100644
--- a/packages/tailwindcss-language-service/src/util/find.ts
+++ b/packages/tailwindcss-language-service/src/util/find.ts
@@ -3,7 +3,7 @@ import type { TextDocument } from 'vscode-languageserver-textdocument'
 import type { DocumentClassName, DocumentClassList, State, DocumentHelperFunction } from './state'
 import lineColumn from 'line-column'
 import { isCssContext, isCssDoc } from './css'
-import { isHtmlContext } from './html'
+import { isHtmlContext, isVueDoc } from './html'
 import { isWithinRange } from './isWithinRange'
 import { isJsxContext } from './js'
 import { dedupeByRange, flatten } from './array'
@@ -97,9 +97,10 @@ export function findClassListsInCssRange(
   state: State,
   doc: TextDocument,
   range?: Range,
+  lang?: string,
 ): DocumentClassList[] {
   const text = getTextWithoutComments(doc, 'css', range)
-  let regex = isSemicolonlessCssLanguage(doc.languageId, state.editor?.userLanguages)
+  let regex = isSemicolonlessCssLanguage(lang ?? doc.languageId, state.editor?.userLanguages)
     ? /(@apply\s+)(?<classList>[^}\r\n]+?)(?<important>\s*!important)?(?:\r|\n|}|$)/g
     : /(@apply\s+)(?<classList>[^;}]+?)(?<important>\s*!important)?\s*[;}]/g
   const matches = findAll(regex, text)
@@ -302,7 +303,7 @@ export async function findClassListsInDocument(
       )),
       ...boundaries
         .filter((b) => b.type === 'css')
-        .map(({ range }) => findClassListsInCssRange(state, doc, range)),
+        .map(({ range, lang }) => findClassListsInCssRange(state, doc, range, lang)),
       await findCustomClassLists(state, doc),
     ]),
   )
@@ -408,14 +409,36 @@ export async function findClassNameAtPosition(
   doc: TextDocument,
   position: Position,
 ): Promise<DocumentClassName> {
-  let classNames = []
+  let classNames: DocumentClassName[] = []
   const positionOffset = doc.offsetAt(position)
   const searchRange: Range = {
     start: doc.positionAt(Math.max(0, positionOffset - 2000)),
     end: doc.positionAt(positionOffset + 2000),
   }
 
-  if (isCssContext(state, doc, position)) {
+  if (isVueDoc(doc)) {
+    let boundaries = getLanguageBoundaries(state, doc)
+
+    let groups = await Promise.all(boundaries.map(async ({ type, range, lang }) => {
+      if (type === 'css') {
+        return findClassListsInCssRange(state, doc, range, lang)
+      }
+
+      if (type === 'html') {
+        return await findClassListsInHtmlRange(state, doc, 'html', range)
+      }
+
+      if (type === 'jsx') {
+        return await findClassListsInHtmlRange(state, doc, 'jsx', range)
+      }
+
+      return []
+    }))
+
+    classNames = dedupeByRange(flatten(groups)).flatMap(
+      (classList) => getClassNamesInClassList(classList, state.blocklist)
+    )
+  } else if (isCssContext(state, doc, position)) {
     classNames = await findClassNamesInRange(state, doc, searchRange, 'css')
   } else if (isHtmlContext(state, doc, position)) {
     classNames = await findClassNamesInRange(state, doc, searchRange, 'html')
diff --git a/packages/tailwindcss-language-service/src/util/getLanguageBoundaries.ts b/packages/tailwindcss-language-service/src/util/getLanguageBoundaries.ts
index 83f59309..7630b652 100644
--- a/packages/tailwindcss-language-service/src/util/getLanguageBoundaries.ts
+++ b/packages/tailwindcss-language-service/src/util/getLanguageBoundaries.ts
@@ -7,8 +7,13 @@ import { isJsDoc } from './js'
 import moo from 'moo'
 import Cache from 'tmp-cache'
 import { getTextWithoutComments } from './doc'
+import { isCssLanguage } from './css'
 
-export type LanguageBoundary = { type: 'html' | 'js' | 'css' | (string & {}); range: Range }
+export type LanguageBoundary = {
+  type: 'html' | 'js' | 'css' | (string & {});
+  range: Range
+  lang?: string
+}
 
 let htmlScriptTypes = [
   // https://v3-migration.vuejs.org/breaking-changes/inline-template-attribute.html#option-1-use-script-tag
@@ -92,6 +97,13 @@ let vueStates = {
     htmlBlockStart: { match: '<template', push: 'htmlBlock' },
     ...states.main,
   },
+
+  cssBlock: {
+    langAttrStartDouble: { match: 'lang="', push: 'langAttrDouble' },
+    langAttrStartSingle: { match: "lang='", push: 'langAttrSingle' },
+    ...states.cssBlock,
+  },
+
   htmlBlock: {
     htmlStart: { match: '>', next: 'html' },
     htmlBlockEnd: { match: '/>', pop: 1 },
@@ -193,5 +205,13 @@ export function getLanguageBoundaries(
 
   cache.set(cacheKey, boundaries)
 
+  for (let boundary of boundaries) {
+    if (boundary.type === 'css') continue
+    if (!isCssLanguage(state, boundary.type)) continue
+
+    boundary.lang = boundary.type
+    boundary.type = 'css'
+  }
+
   return boundaries
 }
diff --git a/packages/vscode-tailwindcss/CHANGELOG.md b/packages/vscode-tailwindcss/CHANGELOG.md
index 04c206c3..cc138c86 100644
--- a/packages/vscode-tailwindcss/CHANGELOG.md
+++ b/packages/vscode-tailwindcss/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Fix crash when class regex matches an empty string (#897)
 - Support Astro's `class:list` attribute by default (#890)
+- Fix hovers and CSS conflict detection in Vue `<style lang="sass">` blocks (#930)
 
 ## 0.10.5