Some more adjustments to make the SL theme closer to original.

services/web/app/views/project/list/side-bar.pug

@@ -1,5 +1,5 @@
 .dropdown(dropdown)
-	a.btn.btn-primary.btn-block.dropdown-toggle(
+	a.btn.btn-primary.sidebar-new-proj-btn.dropdown-toggle(
 		href="#",
 		data-toggle="dropdown",
 		dropdown-toggle

services/web/public/stylesheets/app/project-list.less

@@ -34,6 +34,10 @@
 	.container;
 }
 
+.sidebar-new-proj-btn when (@is-overleaf) {
+	.btn-block;
+}
+
 	.project-list-row {
 		display: flex;
 		flex-direction: column;
@@ -307,7 +311,7 @@ ul.structured-list {
 	}
 }
 
-.project-list-card {
+.project-list-card when (@is-overleaf) {
 	padding: 0 (@line-height-computed / 4);
 }