feat: Add a documentation layout design for public help center portal (#14403)

https://github.com/user-attachments/assets/fc4d15f9-2b54-4627-940f-94772ec739b1

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/portal/application.scss

@@ -5,9 +5,18 @@
 
 @import 'widget/assets/scss/reset';
 @import 'shared/assets/fonts/InterDisplay/inter-display';
+@import 'shared/assets/fonts/inter';
+@import 'dashboard/assets/scss/next-colors';
 
 html,
 body {
+  -moz-osx-font-smoothing: grayscale;
+  -webkit-font-smoothing: antialiased;
+  height: 100%;
+  letter-spacing: 0.2px;
+}
+
+.font-default {
   font-family:
     'InterDisplay',
     -apple-system,
@@ -23,10 +32,6 @@ body {
     'Apple Color Emoji',
     'Segoe UI Emoji',
     'Noto Color Emoji';
-  -moz-osx-font-smoothing: grayscale;
-  -webkit-font-smoothing: antialiased;
-  height: 100%;
-  letter-spacing: 0.2px;
 }
 
 // Taking these utils from tailwind 3.x.x, need to remove once we upgrade
@@ -49,3 +54,7 @@ body {
     }
   }
 }
+
+.turbolinks-progress-bar {
+  background-color: var(--dynamic-portal-color);
+}