Thanks to Stephen McPaul. He's totally right. I tried his method and I was proved wrong. He made a good point about legacy fonts installed locally. Please ignore the rest of this post... LOL
What I'm going to say here is not a popular view - Open Sans is gaining attention and we see more and more sites welcomed the free and open font hosted by Google Webfont. But exactly because the trend keeps going strong, I feel obligated to speak up - as a reader, not a bling-bling designer.
font-family: 'Open Sans', sans-serif;
I wasn't keen to complain at the first glance because, well, SquareSpace is known for their design delicacy. I thought they deliberately chose Open Sans as the body font -and to make it worse, in a very light grey for low contrast - so that the big, dark, legible headers and keywords would stand out. Maybe they designed the typography this way for the reader to skip the paragraphs and to scan through the document quickly.
Then I surfed through SquareSpace Answers (their powerful, useful but hard-to-read knowledge base), the typography became a real problem.
Many times I had to zoom in several times to read the text. I'm thinking, well, they didn't expect their user to post such a long question... right? What about this one:
Please, if you bother, go click that link and see the page for yourself. The Open Sans in light gray small is an eye-killer.
Now I have to think again: SquareSpace is not using Open Sans as the body font on their own blog - that should tell something.
I'm sorry SquareSpace, I didn't meant to finger point at you as a bad example. You are known for your good taste in design, so I expected more from you.
A while ago Wordpress claimed that they're using Open Sans all across their site. I think the decision was less than considerate.
This screen capture tells exactly what I said at the beginning of this article: Open Sans works beautifully as a display or header font. It performs the best when the font size is greater than 15px. Anything goes below is a torture to read. I urge all the web designers including myself to ask our conscience before we make any trendy decision.