masthead_in_motion = 0;

function toggle_masthead( trigger, height ) {
	if( trigger == '0px' )
		if( masthead_in_motion == 0 ) {
			masthead_in_motion = 1;
			if( $('masthead').style.top != '0px' ) 
				new Effect.Move( 'masthead', {y:height, duration:.3, afterFinish:function() {masthead_in_motion = 0; } } );
			else 
				new Effect.Move( 'masthead', {y:( -1 * height ), duration:.3, afterFinish:function() {masthead_in_motion = 0; } } );
			}
	} // end toggle_masthead()