CSS does not reset on navigation (forward/Previous)

Is this a bug???
I have code that changes the properties of a display field basedon a condition.
This works well for the 1st style, but when I page through using navigation, the subsequent records display the same color for everyone following. he value of {tbr} changes so I know the if statement os being executed.

Am I supposed to be resetting CSS somehow in between or is this a bug?

if({dateToday} < {lastViewedDate})
{{tbr} = "Next review for: ";

			?>
		<style> 	
		#id_read_on_nextreview  {
		  color:  green;
		  font-style: italic;
		}
		</style>
		<?php	
}

elseif
({dateToday} > {lastViewedDate} and {lastViewedDate} <> NULL)
{{tbr} = "Review is overdue: ";
?>

		#id_read_on_nextreview  {
		  color:  Red;
		  font-style: italic;
		}
		</style>
		<?php	

}
elseif
({dateToday} == {lastViewedDate})
{{tbr} = "Review due today: ";
?>

		#id_read_on_nextreview  {
		  color:  Orange;
		  font-style: italic;
		}
		</style>
		<?php	
  }