I’m using a Windows 8 tablet (the Linx 10 if you’re curious) and found that the close buttons in Firefox were a bit small and difficult to press.
I’ve fixed this by adding the following to my userChrome.css file:
{% highlight css %} .tab-close-button { border-radius: 20%; background: rgba(0,0,0,0.1) !important; width: 32px !important; height: 32px !important; } {% endhighlight %}