On non-replaced inline elements, line-height
specifies the height that is used to calculate line box height. On replaced inline elements such as buttons or other input elements, line-height
has no effect. [1]
百分比值，竟然是相對于字體
<percentage>
Relative to the font size of the element itself. The computed value is this percentage multiplied by the element's computed font size.Percentage and em values may have unexpected results, see "Notes" section.
