how to change the distance in html code example

Example 1: line spacing css

line-height: 20px; /* 4px +12px + 4px */
/* OR */
line-height: 1.7em; /* 1em = 12px in this case. 20/12 == 1.666666  */

Example 2: how to add space inbetween lines in html

main {
	line-height: 20px:
}