chore: update dependencies and clean up styles

- Added @codemirror/language and @lezer/common as devDependencies in package.json and package-lock.json.
- Removed inline date-calc styling and specific CodeMirror styles from styles.css for a cleaner design.

package.json

@@ -12,6 +12,8 @@
 	"author": "",
 	"license": "MIT",
 	"devDependencies": {
+		"@codemirror/language": "^6.12.1",
+		"@lezer/common": "^1.5.0",
 		"@types/node": "^16.11.6",
 		"@typescript-eslint/eslint-plugin": "5.29.0",
 		"@typescript-eslint/parser": "5.29.0",