Indic text displays with extra spaces on IceWeasel (Firefox) on Linux

When I use indic (Gurmukhi) text, it displays with extra spaces in between. Visit https://blog.hardeep.name/sikhism/20080805/being-blind/ to see through Iceweasel (Firefox) on Linux. Or, is it a problem in my machine confiration? I dont think its a problem on my machine because the wikipedia indic page is correctly rendered, without this problem. In addition, even in WordPress – while editing the post, it shows correctly. The encoding seems to be correctly selected as UTF-8. Please advise.