Css_Absolute and Relative units.txt

Absolute units:
px - Pixel
  pt - Point
  pc - Picas
  in - Inch
  cm - Centimeter
  mm - Millimeter
Relative units:
em - Relative to the font-size of the element
  ex - Relative to the x-height of the current font
  % - Relative to the parent element
  ch - Relative to the width of zero
  rem - Relative to the root element
  vw - The viewport width is relative to 1% of the width viewport (browser window)
  vh - The viewport height is relative to 1% of the height viewport (browser window)
  vmin - The viewport minimum is relative to 1% of the viewport (browser window) for smaller dimension
  vmax - The viewport maximum is relative to 1% of the viewport (browser window) for larger dimension