IconGrid: improve empty-state rendering and animation

When search returns no results, the empty-list state now adopts the
current color theme and animates in. The IconGrid also takes up a
minimum of 80vh vertical space, whether the list is populated or empty.

src/components/IconGrid/IconGrid.css

@@ -1,5 +1,6 @@
 .grid-container {
   padding: 0px 16px 4px;
+  min-height: 80vh;
 }
 
 .grid {
@@ -151,5 +152,6 @@
   flex-direction: column;
   align-items: center;
   justify-content: center;
-  padding: 24px;
+  padding: 0 16px 4px;
+  min-height: 80vh;
 }