line-height

On block level elements, the line-height CSS property specifies the minimal height of line boxes within the element.
On non-replaced inline elements, line-height specifies the height that is used in the calculation of the line box height.
On replaced inline elements, like buttons or other input element, line-height has no effect.

Examples

/* All rules below have the same resultant line height */

div { line-height: 1.2;   font-size: 10pt }   /* number */ 
div { line-height: 1.2em; font-size: 10pt }   /* length */ 
div { line-height: 120%;  font-size: 10pt }   /* percentage */
div { line-height: 12pt;  font-size: 10pt }   /* length */
div { font: 10pt/1.2  Georgia,"Bitstream Charter",serif }

Example

<!DOCTYPE html>
<html>
    <head>
        <style>
            .green {
                font-size: 15px;
                line-height: 1.1;
                border: solid limegreen;
            } .red {
                font-size: 15px;
                line-height: 3.1em;
                border: solid red;
            }
            
        </style>
    </head>
    <body>
        <div class=green>
            Avoid unexpected results by using unitless 
			line-height length and percentage line-heights 
			have poor inheritance behavior ...
        </div>
        <div class=red>
            Avoid unexpected results by using unitless 
			line-height length and percentage line-heights 
			have poor inheritance behavior ...
        </div>
    </body>
</html>