I often use this as an interview question for CSS people: "How would you vertically center a box inside another box." I like it because there's like four correc

I often use this as an interview question for CSS people: "How would you vertically center a box inside another box." I like it because there's like four correct answers, each with drawbacks. The general answers, from worst to best, are usually: 1. margin: auto (wrong) 2. top: 50% (mostly wrong) 3. negative margin-top (correct if you know the size) 4. table-cell or translateY (correct) 5. a correct answer plus a discussion about why it has to be a hack FWIW, when you set everything to "Unknown", this site tells you to use display: table-cell. If you don't have to support IE8, I generally prefer "top: 50%; translate-Y: -50%" [Edited for spacing.]