ensured footer was pinned to bottom of page for new-ish billboard.html & room_scroll.html pages; introduced mobile landscape layout, incl. leftward 'navbar', rightward 'footer'; ensured z-index primacy of #id_kit_btn, which would here appear behind the kit bar when open; other fixes introduced by problems stemming largely from new landscape styling

src/static_src/scss/_billboard.scss

@@ -0,0 +1,28 @@
+html:has(body.page-billboard) {
+    overflow: hidden;
+}
+
+body.page-billboard {
+    overflow: hidden;
+
+    .container {
+        overflow: hidden;
+        display: flex;
+        flex-direction: column;
+        flex: 1;
+        min-height: 0;
+    }
+
+    .row {
+        flex-shrink: 0;
+        margin-bottom: -1rem;
+    }
+}
+
+.billboard-page {
+    flex: 1;
+    min-width: 0;
+    overflow-y: auto;
+    position: relative;
+    padding: 0.75rem;
+}