fix(toolbar): position toolbar relative and add z-index

Author: brandyscarney

src/components/app/structure.scss

@@ -18,7 +18,7 @@ $z-index-navbar-section:         10;
 $z-index-page-container:         0;
 $z-index-selected-tab:           1;
 $z-index-toolbar:                10;
-$z-index-toolbar-background:     -1;
+$z-index-toolbar-background:     0;
 
 $z-index-toolbar-border:         20;
 $z-index-list-border:            50;
@@ -183,6 +183,11 @@ ion-header {
   width: 100%;
 }
 
+ion-toolbar {
+  position: relative;
+  z-index: $z-index-toolbar;
+}
+
 ion-footer {
   position: absolute;
   bottom: 0;
@@ -250,4 +255,4 @@ ion-content.js-scroll > scroll-content {
 [nav-portal],
 [tab-portal] {
   display: none;
-}
+}