Secure website?

When I ordered my Mixbooks using my credit card, I noticed that the yellow padlock indicating a secure site does not appear on your site. I entered my cc no. and just stopped short of clicking on the order button although it might have gone through anyway. It's not that I don't want to buy my photobooks but I don't want to put my credit card at risk! Please let me know whether your site is a secure one for purchasing from you!