diff --git a/client/src/app.vue b/client/src/app.vue
index db21f53..2b04761 100644
--- a/client/src/app.vue
+++ b/client/src/app.vue
@@ -103,7 +103,7 @@ import * as monaco from 'monaco-editor'
 import jsonWorker from "monaco-editor/esm/vs/language/json/json.worker?worker";
 import { Splitpanes, Pane } from 'splitpanes';
 import 'splitpanes/dist/splitpanes.css'
-import { setupJSONata } from './setupMonaco'
+import { setupLanguages } from './setupMonaco'
 
 enum ColorTheme {
     Auto = "auto",
@@ -159,19 +159,23 @@ export default defineComponent({
     watch: {
         outputFormat() {
             this.saveConfigurationToLocalStorage();
-            this.onEditorChange();
+            this.onEditorChangeLanguage(false);
+            this.onEditorChangeContent();
         },
         inputFormat() {
             this.saveConfigurationToLocalStorage();
-            this.onEditorChange();
+            this.onEditorChangeLanguage(true);
+            this.onEditorChangeContent();
         },
         csvInputDelimiter() {
             this.saveConfigurationToLocalStorage();
-            this.onEditorChange();
+            this.onEditorChangeLanguage(true);
+            this.onEditorChangeContent();
         },
         csvOutputDelimiter() {
             this.saveConfigurationToLocalStorage();
-            this.onEditorChange();
+            this.onEditorChangeLanguage(false);
+            this.onEditorChangeContent();
         },
         autoRefresh() {
             this.saveConfigurationToLocalStorage();
@@ -182,6 +186,26 @@ export default defineComponent({
         }
     },
     methods: {
+        onEditorChangeLanguage(isInput: boolean) {
+            const editor = toRaw(isInput ? this.monacoInput : this.monacoResult);
+            const model = editor?.getModel();
+            if (!model) {
+                return;
+            }
+            let language = isInput ? this.inputFormat : this.outputFormat;
+            const mode = this.isLight ? 'light' : 'dark';
+            let theme = `${language}-${mode}`;
+            let delimiter = null;
+
+            if (language == 'csv') {
+                delimiter = isInput ? this.csvInputDelimiter : this.csvOutputDelimiter;
+                language = `${language}-${delimiter}`;
+            }
+
+            console.log({ language, theme })
+            // monaco.editor.setTheme(theme)
+            monaco.editor.setModelLanguage(model, language)
+        },
         resized() {
             this.saveConfigurationToLocalStorage();
         },
@@ -216,7 +240,7 @@ export default defineComponent({
         },
         initializeEditors() {
             if (!window.MonacoEnvironment) {
-                setupJSONata();
+                setupLanguages();
 
                 window.MonacoEnvironment = {
                     getWorker: function (): Promise<Worker> | Worker {
@@ -260,13 +284,13 @@ export default defineComponent({
             }));
 
             this.monacoInput.onDidChangeModelContent(() => {
-                this.onEditorChange()
+                this.onEditorChangeContent()
             });
             this.monacoExpression.onDidChangeModelContent(() => {
-                this.onEditorChange()
+                this.onEditorChangeContent()
             });
         },
-        onEditorChange() {
+        onEditorChangeContent() {
             if (this.autoRefresh && this.initialized) {
                 if (this.timer) {
                     clearTimeout(this.timer);
@@ -333,7 +357,7 @@ export default defineComponent({
         },
         setErrorMarker(editor: monaco.editor.IStandaloneCodeEditor, start: number, end: number, message: string) {
             const model = editor.getModel();
-            
+
             if (!model) {
                 return;
             }
diff --git a/client/src/setupMonaco.ts b/client/src/setupMonaco.ts
index e67a0e9..639514f 100644
--- a/client/src/setupMonaco.ts
+++ b/client/src/setupMonaco.ts
@@ -257,13 +257,33 @@ function setupJSONata() {
             }
         }
     })
+}
+
+function setupCsv(delimiter: string) {
+    const name = `csv-${delimiter}`;
+    monaco.languages.register({ id: name });
+
+    monaco.languages.setMonarchTokensProvider(name, {
+        tokenizer: {
+            root: [
+                [new RegExp(`[^${delimiter}]+`), 'csv-column'], // /[^,]+/
+                [new RegExp(`${delimiter}`), 'csv-delimiter'], // /,/
+            ]
+        }
+    });
 
+}
+
+function setupTheme() {
     // Define a new theme that contains only rules that match this language
     monaco.editor.defineTheme('jsonataTheme-light', {
         base: 'vs',
         inherit: true,
         rules: [
-            { token: 'variable', foreground: 'ff4000' },
+            { token: 'variable', foreground: 'ff4000', background: '000000' },
+            { token: 'csv-column', foreground: '000000' , background: '000000'},
+            { token: 'csv-delimiter', foreground: 'ff4000', background: '000000' }
+
         ],
         colors: {
             // "editor.background": '#fffffb'
@@ -274,6 +294,8 @@ function setupJSONata() {
         inherit: true,
         rules: [
             { token: 'variable', foreground: 'ff4000' },
+            { token: 'csv-column', foreground: 'ffffff' },
+            { token: 'csv-delimiter', foreground: 'ff4000' }
         ],
         colors: {
             // "editor.background": '#fffffb'
@@ -281,4 +303,12 @@ function setupJSONata() {
     });
 }
 
-export { setupJSONata }
+function setupLanguages() {
+    setupJSONata();
+    setupCsv(';');
+    setupCsv(',');
+    setupCsv('\t');
+    setupTheme();
+}
+
+export { setupLanguages }