CSS倒数第二个元素

Question

如何选择一组兄弟姐妹中的最后一个元素？在以下跨度3和跨度7的示例中。

span:nth-last-of-type(???)

<div>
  <span>Span 1!</span>
  <span>Span 2</span>
  <span>Span 3!</span>
  <h1>Header 2</h1>
  <span>Span 4</span>
  <span>Span 5!</span>
  <span>Span 6</span>
  <span>Span 7!</span>
  <h1>Header 2</h2>
</div>