homogenized modals - add addressbook modal

src/sass/main.scss

@@ -863,7 +863,7 @@ ul.manage li {
 .header-modal {
   background: #fff;
   width: 100%;
-  padding: 0.8rem;
+  padding-top: 60px;
   position: relative;
 }
 
@@ -1974,11 +1974,10 @@ to prevent collapsing during animation*/
 }
 
 .modal-content {
-  position: fixed;
+  position: relative;
   overflow-y: auto;
   height: 100%;
   width: 100%;
-  top: 45px;
   padding-bottom: 50px;
   -webkit-transform: translate3d(0, 0, 0);
   background: #f6f7f9;