Remove padding from CSS round() function example (#37183)

Remove padding from example

Messes with the example, as the inspector shows a 10px difference not mentioned in the description.

files/en-us/web/css/round/index.md

@@ -113,7 +113,6 @@ div.box {
   width: 100px;
   height: 100px;
   background: lightblue;
-  padding: 5px;
   --rounding-interval: 25px;
 }
 ```