html单位

http://blog.csdn.net/u010408889/article/details/47781297

• px to em:Example: 12px / 16px = .75em
• px to %:Example: 12px / 16px * 100 = 75%
• px to pt:Example: 16px * 72 (72 points = 1 inch) / 96 (96 pixels
• per inch in Windows, 72 in Mac) = 12pt
• em to px:Example: .75em * 16px = 12px
• em to %:Example: .75em * 100 = 75%
• % to px:Example: 75 * 16px / 100 = 12px
• % to em:Example: 75 / 100 = .75em
• pt to px:Example: 12pt * 96ppi / 72ppi = 16px