Set max width on error page and include Last login on error page

- Updated error_base template so that it contained the Root Vue component, which was the reason that the last login was not previously displaying
- Deleted unused css
- Created css variable max-page-width for use on the error page, topbar, and other full width elements

styles/components/_error_page.scss

@@ -1,8 +1,13 @@
 .error-page {
-  max-width: 475px;
-  margin: auto;
+  max-width: $max-page-width;
 
   .panel {
+    box-shadow: none;
+    background-color: unset;
+    border: none;
+    max-width: 475px;
+    margin: auto;
+
     &__heading {
       text-align: center;
       padding: $gap 0;
@@ -15,17 +20,6 @@
         margin-bottom: $gap;
       }
     }
-
-    &__body {
-      padding: $gap * 2;
-      margin: 0;
-
-      hr {
-        width: 80%;
-        margin: auto;
-        margin-bottom: $gap * 3;
-      }
-    }
   }
 
   .icon {

styles/components/_topbar.scss

@@ -12,7 +12,7 @@
     flex-direction: row;
     align-items: stretch;
     justify-content: space-between;
-    max-width: 1190px;
+    max-width: $max-page-width;
 
     a {
       color: $color-white;

styles/core/_variables.scss

@@ -19,6 +19,7 @@ $sidenav-collapsed-width: 10rem;
 $max-panel-width: 90rem;
 $home-pg-icon-width: 6rem;
 $large-spacing: 4rem;
+$max-page-width: $max-panel-width + $sidenav-expanded-width + $large-spacing;
 
 /*
  * USWDS Variables