chore(docs): fix layout between 769px and 991px

Left nav and main content were tucked slightly under the version picker / breadcrumb navbar

Closes angular#6474
Closes angular#7079

Author: Narretz

docs/app/assets/css/docs.css

@@ -572,6 +572,15 @@ ul.events > li {
   margin-bottom:40px;
 }
 
+@media only screen and (min-width: 769px) and (max-width: 991px) {
+  .main-body-grid {
+    margin-top: 160px;
+  }
+  .main-body-grid > .grid-left {
+    top: 160px;
+  }
+}
+
 @media only screen and (max-width : 768px) {
   .picker, .picker select {
     width:auto;