fix minor formatting issue

content/docs/reference-dom-elements.md

@@ -99,6 +99,7 @@ function HelloWorldComponent() {
   return <div style={divStyle}>Hello World!</div>;
 }
 ```
+
 Sometimes you _do_ want to keep the CSS properties unitless. Here's a list of properties that won't get the automatic "px" suffix:
 
 - `animationIterationCount`