Content box of 'table-cell' isn't recalculated to reflect a percentage 'padding' value applied to that element

Live Example

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec eget magna quis dolor lobortis tristique. Nam fermentum imperdiet lorem. Quisque vitae neque sagittis mi faucibus laoreet. Nulla id enim. Donec ut orci nec erat euismod semper. Mauris sem. Donec blandit elit sed mauris. Pellentesque eget nisl eu purus dictum pretium. Aliquam erat volutpat. Suspendisse sodales, sapien vitae aliquet aliquam, nulla metus tempor tortor, elementum adipiscing tortor massa tristique erat. Morbi non nunc sit amet enim pellentesque elementum. Nam urna. Ut eu nulla sit amet ante egestas mollis. Mauris sollicitudin nunc sed turpis. Praesent sed enim et magna imperdiet commodo. Cras accumsan metus gravida ante. Curabitur blandit neque vitae tellus. Vivamus ut nisl imperdiet magna ultrices vehicula.

Expected Results

The computed width of the content area should be re-calculated when a horizontal padding value is applied, leading to no overflowing content.

Actual Results

The width of the content area isn't recalculated, leading to the content being overflowed outside of it's containing box.