write the end text in a span and find that the font is offset downward relative to the space where the span is located. I only use the line-height setting to center the span relative to the parent, but the font inside is still offset downward relative to the span.
but this won"t happen if I rewrite a demo. Please give me your advice.

    .header-nav{
      float: left;
      width: 200px;
      height: 40px;
      background-color: lightgrey;
      span{
        line-height: 40px;
        font-size: 20px;
        background-color: red;
      }
    }