Check out example codes for "line spacing css". It will help you in understanding the concepts better.

Code Example 1

/* Keyword value */
line-height: normal;

/* Unitless values: use this number multiplied
by the element's font size */
line-height: 3.5;

/* <length> values */
line-height: 3em;

/* <percentage> values */
line-height: 34%;

/* Global values */
line-height: inherit;
line-height: initial;
line-height: unset;

Code Example 2

div.a {
  line-height: normal;
}

div.b {
  
    line-height: 1.6;
}

div.c {
  line-height: 
    80%;
}

div.d {
  line-height: 200%;
}

Code Example 3

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

Code Example 4

.green {
  line-height: 1.1;
  border: solid limegreen;
}

.red {
  line-height: 1.1em;
  border: solid red;
}

h1 {
  font-size: 30px;
}

.box {
  width: 18em;
  display: inline-block;
  vertical-align: top;
  font-size: 15px;
}

Code Example 5

<div class="box green">
 <h1>Avoid unexpected results by using unitless line-height.</h1>
  length and percentage line-heights have poor inheritance behavior ...
</div>

<div class="box red">
 <h1>Avoid unexpected results by using unitless line-height.</h1>
  length and percentage line-heights have poor inheritance behavior ...
</div>

<!-- The first <h1> line-height is calculated from its own font-size   (30px × 1.1) = 33px  --> 
<!-- The second <h1> line-height results from the red div's font-size  (15px × 1.1) = 16.5px,  probably not what you want -->

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