make there not be two scroll bars sometimes

src/components/library/library.css

@@ -4,10 +4,11 @@
 .library-scroll-grid {
     display: flex;
     justify-content: center;
+    align-content: flex-start;
     background: $ui-pane-gray;
     flex-grow: 1;
     flex-wrap: wrap;
-    overflow-y: scroll;
-    height: 100%;
+    overflow-y: auto;
+    height: calc(100% - $library-header-height);
     padding: 0.5rem;
 }

src/components/modal/modal.css

@@ -15,7 +15,7 @@
 .full-modal-content {
     position: absolute;
     outline: none;
-    overflow-y: scroll;
+    overflow-y: auto;
     -webkit-overflow-scrolling: 'touch';
     user-select: none;
     height: 100%;
@@ -37,6 +37,7 @@ $sides: 20rem;
     flex-direction: row;
     flex-wrap: nowrap;
     justify-content: flex-start;
+    height: $library-header-height;
 
     box-sizing: border-box;
     width: 100%;

src/css/units.css

@@ -5,3 +5,5 @@ $sprites-per-row: 5;
 $menu-bar-height: 3rem;
 $sprite-info-height: 5.25rem; /* @todo: SpriteInfo isn't explicitly set to this height yet */
 $stage-menu-height: 3rem;
+
+$library-header-height: 4.375rem;
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