Update article.md

"starts to bug..." -> "becomes buggy..."

I am not aware of "bug" being used as a verb in IT, but if it is, this is the first time I recall seeing it, so I would say it's probably not common.

Anyway, using it as a verb kind of bugged me a little.

Author: paroche

2-ui/1-document/09-size-and-scroll/article.md

@@ -245,7 +245,7 @@ Why should we use geometry properties instead? There are two reasons:
 
     From the CSS standpoint, `width:auto` is perfectly normal, but in JavaScript we need an exact size in `px` that we can use in calculations. So here CSS width is useless.
 
-And there's one more reason: a scrollbar. Sometimes the code that works fine without a scrollbar starts to bug with it, because a scrollbar takes the space from the content in some browsers. So the real width available for the content is *less* than CSS width. And `clientWidth/clientHeight` take that into account.
+And there's one more reason: a scrollbar. Sometimes the code that works fine without a scrollbar becomes buggy with it, because a scrollbar takes the space from the content in some browsers. So the real width available for the content is *less* than CSS width. And `clientWidth/clientHeight` take that into account.
 
 ...But with `getComputedStyle(elem).width` the situation is different. Some browsers (e.g. Chrome) return the real inner width, minus the scrollbar, and some of them (e.g. Firefox) -- CSS width (ignore the scrollbar). Such cross-browser differences is the reason not to use `getComputedStyle`, but rather rely on geometry properties.