CSS style cleanup

data/website_gallery/css/modal.css

@@ -35,6 +35,7 @@
 }
 
 .nav {
+  height: var(--navigation-bar-height);
   justify-content: center;
   align-items: center;
   display: flex;
@@ -42,6 +43,7 @@
 }
 
 .slider {
+    height: calc(100vh - var(--navigation-bar-height));
     position: relative;
     width: 100vw;
     touch-action: none;

data/website_gallery/css/style.css

@@ -35,14 +35,13 @@ body {
     box-shadow: 0 1vw 4vw 1vw rgba(0,0,0,0.6);
 }
 
-.nav {
-  height: 5vh;
-  background-color: rgba(60,60,60, 0.4);
-  color: #ccc;
+.viewer {
+    --navigation-bar-height: 5vh;
 }
 
-.slider {
-    height: 95vh; /* remaining vh after nav vh */
+.nav {
+  background-color: rgba(60,60,60, 0.4);
+  color: #ccc;
 }
 
 .navgrid {