Add styling for upcoming multitasking chapter

blog/static/css/main.css

@@ -86,6 +86,10 @@ main img {
   border: 2px solid #f66;
 }
 
+.posts.multitasking {
+  border: 2px solid #556b2f;
+}
+
 .posts hr {
   margin: 2rem 0;
 }
@@ -121,6 +125,10 @@ main img {
   color: #f33;
 }
 
+.post-category.multitasking {
+  color: #556b2f;
+}
+
 .post-footer-support {
   margin-top: 2rem;
 }