line-height

/* Keyword value */
line-height: normal; // = 1.2 (depending on the element's font-family)

body {
    font-size: 16px;
    line-height: 1.5; //16 * 1.5 = 24px
}

/*em and rem*/
html {
    font-size: 12px;
}
.remExample {
    font-size: 16px;
    line-height: 1.5rem; /* line-height will be 12 * 1.5 = 18px */
}
.emExample {
    font-size: 16px;
    line-height: 1.5em; /* line-height will be 16 * 1.5 = 24px */
}

/*percentage*/
body {
    font-size: 12px;
}
.percentage {
    font-size: 16px;
    line-height: 150%; /* line-height will be 16 * 1.5 = 24px */
}

/*pixel */
body {
    font-size: 16px;
}

.pixel {
    line-height: 12px;
}