Update style.css

style.css

@@ -1,21 +1,26 @@
-body {
+* {
     margin: 0;
-    overflow: hidden;
+    padding: 0;
+    box-sizing: border-box;
+}
+
+body {
     display: flex;
     justify-content: center;
     align-items: center;
     height: 100vh;
     background-color: #000;
+    overflow: hidden;
 }
 
 #gameArea {
     position: relative;
-    width: 100%;
-    height: 100%;
+    width: 100vw;
+    height: 100vh;
     background-color: #333;
 }
 
-#paddleLeft, #paddleRight {
+.paddle {
     position: absolute;
     width: 10px;
     height: 80px;