A thickness attribute can contain a single value to represent a desired thickness in units. Alternatively, it can specify one or more specific thickness attributes:

  • top
  • left
  • bottom
  • right

For example, a border with a thickness of 5 units in all dimensions could be specified as border: 5, but could also be specified as border: { top: 5, left: 5, bottom: 5, right: 5 }. And of course, in the latter model, different values can be provided for each sub-attribute.