Fix post-section-navigator style issue

Author: FawzyMokhtar

src/styles/components/_post-article.scss

@@ -1,4 +1,5 @@
 app-post-article {
+  width: 100%;
   article {
     margin-top: 1rem;
   }

src/styles/components/angular/_app-main.scss

@@ -2,4 +2,9 @@ app-main {
   display: flex;
   flex-direction: row;
   width: 100%;
+
+  :nth-child(3) {
+    display: block;
+    width: 100%;
+  }
 }