Thank you very much for your response & explanation.
Reason I need display:inline is that I am trying to text-align:center the menu item links. As the menu item links text are dynamic, width of each item could change anytime.
Some alternatives is that I could use padding or position % to push it to the center, but these methods have some other limitations for me as well.
I am just wondering if there is any other way to check if the CSS is disabled?