diff --git a/userContent.css b/userContent.css
index 8941351..d8f2d5b 100644
--- a/userContent.css
+++ b/userContent.css
@@ -16,4 +16,92 @@
       height: 100% !important; /* Original: 48px */
     }
   }
+
+  /** Error Page - Restore illustrations **************************************/
+  @-moz-document url-prefix("about:neterror"),
+  url("about:restartrequired"), url("chrome://browser/content/aboutRestartRequired.xhtml"),
+  url("about:sessionrestore"),  url(chrome://browser/content/aboutSessionRestore.xhtml) {
+    /* Illustrations Position */
+    #errorPageContainer, .description-wrapper {
+      min-height: 300px;
+      background-position: left center;
+      background-repeat: no-repeat;
+      background-size: 38%;
+    }
+
+    #errorPageContainer {
+      display: flex;
+      flex-direction: column;
+    }
+    .description-wrapper {
+      padding-inline-start: 38%;
+    }
+
+    /* Container */
+    .container {
+      min-width: var(--in-content-container-min-width); /* 13em */
+      max-width: var(--in-content-container-max-width); /* 52em */
+    }
+
+    /* Text Position */
+    #text-container {
+      margin: auto;
+      padding-inline-start: 38%;
+    }
+  }
+
+  @-moz-document url-prefix("about:neterror?e=dnsNotFound") {
+    #errorPageContainer {
+      background-image: url("chrome://browser/skin/illustrations/error-server-not-found.svg");
+    }
+  }
+  @-moz-document url-prefix("about:neterror?e=malformedURI") {
+    #errorPageContainer {
+      background-image: url("chrome://browser/skin/illustrations/error-malformed-url.svg");
+    }
+  }
+  @-moz-document url("about:restartrequired"), url("chrome://browser/content/aboutRestartRequired.xhtml") {
+    #errorPageContainer {
+      background-image: url("chrome://browser/skin/illustrations/error-connection-failure.svg");
+    }
+  }
+  @-moz-document url("about:sessionrestore"), url(chrome://browser/content/aboutSessionRestore.xhtml) {
+    .description-wrapper {
+      background-image: url("chrome://browser/skin/illustrations/error-session-restore.svg");
+    }
+  }
+
+  @-moz-document url-prefix("about:neterror?e=fileNotFound") {
+    @media (min-width: 970px) {
+      .title {
+        background-image:
+          url("chrome://global/skin/icons/info.svg") !important;
+      }
+    }
+
+    #text-container {
+      padding-inline-start: 0;
+    }
+  }
+  @-moz-document url-prefix("about:tabcrashed") {
+    @media (min-width: 970px) {
+      .title {
+        background-image: url("chrome://browser/skin/tab-crashed.svg") !important;
+      }
+    }
+  }
+  @-moz-document url("about:robots"), url("chrome://browser/content/aboutRobots.xhtml") {
+    @media (min-width: 970px) {
+      .title {
+        background-image: url("chrome://browser/content/aboutRobots-icon.png") !important;
+      }
+    }
+  }
+  @-moz-document url("about:welcomeBack"), url("chrome://browser/content/aboutWelcomeBack.xhtml") {
+    @media (min-width: 970px) {
+      .title {
+        background-image: url("chrome://browser/skin/welcome-back.svg") !important;
+      }
+    }
+  }
 }