/**
 * Returns runner's top position.
 */
function getRunnerTop(elRunner)
{
	return parseInt(elRunner.style.top, 10);
}

/**
 * Returns runner's height
 */
function getRunnerHeinght(elRunner)
{
	return parseInt(elRunner.clientHeight, 10);
}

/**
 * Move runner to start point -- under the container.
 */
function moveRunnerToStart(elRunner, startPosition)
{
	elRunner.style.top = startPosition + "px";
}

/**
 * Move runner on one step.
 */
function moveRunner(elRunner, step)
{
	elRunner.style.top = (getRunnerTop(elRunner) - step) + "px";
}