Set html/body background to black and disable overscroll bounce

- Added background-color: #000000 to prevent white flash on overscroll
- Added overscroll-behavior: none to disable elastic bounce effect

client/src/index.css

@@ -4,6 +4,12 @@
 	box-sizing: border-box;
 }
 
+html,
+body {
+	background-color: #000000;
+	overscroll-behavior: none;
+}
+
 html {
 	scroll-behavior: smooth;
 }