//me
Absolute Lengths:
cm = centimeters
mm = millimeters
in = inches (1in = 96px = 2.54cm)
px = pixels (1px = 1/96th of 1in)
pt = points (1pt = 1/72 of 1in)
pc = picas (1pc = 12 pt)
Relative Lengths:
em = Relative to the font-size of the element (2em means 2 times the size of the current font)
ex = Relative to the x-height of the current font (rarely used)
ch = Relative to the width of the "0" (zero)
rem = Relative to font-size of the root element
vw = Relative to 1% of the width of the viewport*
vh = Relative to 1% of the height of the viewport*
vmin = Relative to 1% of viewport's* smaller dimension
vmax = Relative to 1% of viewport's* larger dimension
% = Relative to the parent element