diff --git a/manifest.json b/manifest.json
index 8c3f310..faccaa5 100644
--- a/manifest.json
+++ b/manifest.json
@@ -24,7 +24,8 @@
   "permissions": [
     "storage",
     "tabs",
-    "webNavigation"
+    "webNavigation",
+    "scripting"
   ],
   "background": {
     "service_worker": "service_workers/background.js", "type": "module"
@@ -33,5 +34,6 @@
   "web_accessible_resources": [{
     "matches": ["<all_urls>"],
     "resources": ["utils.js"]
-  }]
+  }],
+  "host_permissions": ["https://*.twitter.com/*"]
 }
diff --git a/service_workers/background.js b/service_workers/background.js
index 0d3ae03..6623c3a 100644
--- a/service_workers/background.js
+++ b/service_workers/background.js
@@ -8,18 +8,39 @@ chrome.webNavigation.onCommitted.addListener(async () => {
 })
 
 chrome.runtime.onInstalled.addListener(async () => {
+    const openTwitterTabs = await chrome.tabs.query({ url: 'https://*.twitter.com/*' })
+
     const versionInStorage = await chrome.storage.sync.get('version')
-    if(Object.keys(versionInStorage).length === 0) {
+    const foundVersionInStorage = Object.keys(versionInStorage).length === 1
+    if(!foundVersionInStorage) {
         await chrome.storage.sync.clear()
         setDefaultRules()
+
+        injectContentScriptInOpenTwitterTabs(openTwitterTabs)
+
         return
     }
 
     const rulesInStorage = await chrome.storage.sync.get('CSSRulesArrayOfObjectsWithNames')
     const foundStoredRules = Object.keys(rulesInStorage).length > 0
     if (!foundStoredRules) setDefaultRules()
+    
+    injectContentScriptInOpenTwitterTabs(openTwitterTabs)
 })
 
+/**
+ * 
+ * @param {chrome.tabs.Tab[]} tabs 
+ */
+function injectContentScriptInOpenTwitterTabs(tabs) {
+    for (const tab of tabs) {
+        chrome.scripting.executeScript({
+            target: { tabId: tab.id },
+            files: ['scripts/content.js'] 
+        })
+    }
+}
+
 chrome.storage.onChanged.addListener((changes, areaName) => {
     let [[key, { oldValue, newValue }]] = Object.entries(changes);