diff --git a/src/lsp/providers/diagnosticsProvider.ts b/src/lsp/providers/diagnosticsProvider.ts
deleted file mode 100644
index 51565e9c5cb5a4d1f3291a37a4c28d99a220d47d..0000000000000000000000000000000000000000
--- a/src/lsp/providers/diagnosticsProvider.ts
+++ /dev/null
@@ -1,79 +0,0 @@
-import {
-  TextDocument,
-  Diagnostic,
-  DiagnosticSeverity,
-} from 'vscode-languageserver'
-import { State } from '../util/state'
-import { isCssDoc } from '../util/css'
-import { findClassNamesInRange } from '../util/find'
-import { getClassNameParts } from '../util/getClassNameAtPosition'
-const dlv = require('dlv')
-
-function provideCssDiagnostics(state: State, document: TextDocument): void {
-  const classNames = findClassNamesInRange(document)
-
-  let diagnostics: Diagnostic[] = classNames
-    .map(({ className, range }) => {
-      const parts = getClassNameParts(state, className)
-      if (!parts) return null
-      const info = dlv(state.classNames.classNames, parts)
-      let message: string
-      if (info.__context && info.__context.length > 0) {
-        if (info.__context.length === 1) {
-          message = `\`@apply\` cannot be used with \`.${className}\` because it is nested inside of an at-rule (${info.__context[0]}).`
-        } else {
-          message = `\`@apply\` cannot be used with \`.${className}\` because it is nested inside of at-rules (${info.__context.join(
-            ', '
-          )}).`
-        }
-      } else if (info.__pseudo && info.__pseudo.length > 0) {
-        if (info.__pseudo.length === 1) {
-          message = `\`@apply\` cannot be used with \`.${className}\` because its definition includes a pseudo-selector (${info.__pseudo[0]})`
-        } else {
-          message = `\`@apply\` cannot be used with \`.${className}\` because its definition includes pseudo-selectors (${info.__pseudo.join(
-            ', '
-          )})`
-        }
-      }
-
-      if (!message) return null
-
-      return {
-        severity: DiagnosticSeverity.Error,
-        range,
-        message,
-        // source: 'ex',
-      }
-    })
-    .filter(Boolean)
-
-  // if (state.editor.capabilities.diagnosticRelatedInformation) {
-  //   diagnostic.relatedInformation = [
-  //     {
-  //       location: {
-  //         uri: document.uri,
-  //         range: Object.assign({}, diagnostic.range),
-  //       },
-  //       message: '',
-  //     },
-  //     {
-  //       location: {
-  //         uri: document.uri,
-  //         range: Object.assign({}, diagnostic.range),
-  //       },
-  //       message: '',
-  //     },
-  //   ]
-  // }
-
-  state.editor.connection.sendDiagnostics({ uri: document.uri, diagnostics })
-}
-
-export async function provideDiagnostics(
-  state: State,
-  document: TextDocument
-): Promise<void> {
-  if (isCssDoc(state, document)) {
-    return provideCssDiagnostics(state, document)
-  }
-}
diff --git a/src/lsp/server.ts b/src/lsp/server.ts
index 480aa289e7b5035e907891fd287bf45baeddd159..b28b1bad9d226222f5d9e24472c9d8d698df6187 100644
--- a/src/lsp/server.ts
+++ b/src/lsp/server.ts
@@ -26,7 +26,6 @@ } from './providers/completionProvider'
 import { provideHover } from './providers/hoverProvider'
 import { URI } from 'vscode-uri'
 import { getDocumentSettings } from './util/getDocumentSettings'
-import { provideDiagnostics } from './providers/diagnosticsProvider'
 
 let state: State = { enabled: false }
 let connection = createConnection(ProposedFeatures.all)
@@ -45,9 +44,6 @@   getDocumentSettings(state, event.document.uri)
 })
 documents.onDidClose((event) => {
   documentSettings.delete(event.document.uri)
-})
-documents.onDidChangeContent((change) => {
-  provideDiagnostics(state, change.document)
 })
 documents.listen(connection)
 
@@ -68,10 +64,6 @@           : {},
       capabilities: {
         configuration:
           capabilities.workspace && !!capabilities.workspace.configuration,
-        diagnosticRelatedInformation:
-          capabilities.textDocument &&
-          capabilities.textDocument.publishDiagnostics &&
-          capabilities.textDocument.publishDiagnostics.relatedInformation,
       },
     }
 
diff --git a/src/lsp/util/css.ts b/src/lsp/util/css.ts
index d1acbea2b4e6e166e57d7d604ac2e615d1e94a0b..84b788889c876707b4201ba3d2093b8bb472dd2f 100644
--- a/src/lsp/util/css.ts
+++ b/src/lsp/util/css.ts
@@ -11,8 +11,8 @@   'scss',
   'stylus',
 ]
 
-import { TextDocument, Position } from 'vscode-languageserver'
 import { State } from './state'
+
   const userCssLanguages = Object.keys(
     state.editor.userLanguages
   ).filter((lang) => CSS_LANGUAGES.includes(state.editor.userLanguages[lang]))
diff --git a/src/lsp/util/find.ts b/src/lsp/util/find.ts
index 17b6a127654ae8b748941e828167512078286361..3fb04517624e5208d2b2c4f2152e3285e1bb9d8a 100644
--- a/src/lsp/util/find.ts
+++ b/src/lsp/util/find.ts
@@ -72,7 +72,7 @@ }
 
 export function findClassNamesInRange(
   doc: TextDocument,
-  range?: Range
+  range: Range
 ): DocumentClassName[] {
   const classLists = findClassListsInRange(doc, range)
   return [].concat.apply(
@@ -111,11 +111,10 @@ }
 
 export function findClassListsInRange(
   doc: TextDocument,
-  range?: Range
+  range: Range
 ): DocumentClassList[] {
   const text = doc.getText(range)
   const matches = findAll(/(@apply\s+)(?<classList>[^;}]+)[;}]/g, text)
-  const globalStart: Position = range ? range.start : { line: 0, character: 0 }
 
   return matches.map((match) => {
     const start = indexToPosition(text, match.index + match[1].length)
@@ -128,16 +127,16 @@       classList: match.groups.classList,
       range: {
         start: {
 import { TextDocument, Range, Position } from 'vscode-languageserver'
-  let matches: RegExpMatchArray[] = []
+  for (let i = arr.length - 1; i >= 0; --i) {
 import { TextDocument, Range, Position } from 'vscode-languageserver'
+import { DocumentClassName, DocumentClassList } from './state'
-  while ((match = re.exec(str)) !== null) {
         },
         end: {
 import { TextDocument, Range, Position } from 'vscode-languageserver'
-import { TextDocument, Range, Position } from 'vscode-languageserver'
+import { DocumentClassName, DocumentClassList } from './state'
 import { TextDocument, Range, Position } from 'vscode-languageserver'
 import { TextDocument, Range, Position } from 'vscode-languageserver'
-import { TextDocument, Range, Position } from 'vscode-languageserver'
+import { DocumentClassName, DocumentClassList } from './state'
 import { DocumentClassName, DocumentClassList } from './state'
         },
       },
diff --git a/src/lsp/util/state.ts b/src/lsp/util/state.ts
index fc474eb4e418d6628542a8d78c69e54d6d9288b6..daaa0501c05f20e0e88dc85c4357533d26e4a74d 100644
--- a/src/lsp/util/state.ts
+++ b/src/lsp/util/state.ts
@@ -21,7 +21,6 @@   globalSettings: Settings
   userLanguages: Record<string, string>
   capabilities: {
     configuration: boolean
-    diagnosticRelatedInformation: boolean
   }
 }