ng(1);
  step(0);
  that.on("hashchange", hashchange);
});

function resize() {
  d3.select("body").style("margin-top", (window.innerHeight - 800) / 3 + "px");
}

function step(delta) {
  if (delta > 0) {
    var temp = previous;
    previousIndex = currentIndex;
    previous = current.attr("id", "previous");
    currentIndex = nextIndex;
    current = next.attr("id", "current");
    nextIndex = nextIndex >= slides.length - 1 ? 0 : nextIndex + 1;
    next = temp.attr("id", "next");
  } else if (delta < 0) {