Check out example codes for "select even child css". It will help you in understanding the concepts better.

Code Example 1

li:nth-child(even) { /* Selects only even elements */
    color: green;   
}

Code Example 2

tr:nth-child(even) {background: #CCC}
tr:nth-child(odd) {background: #FFF}

Code Example 3

/* Selects the second <li> element in a list */
li:nth-child(2) { 
  color: lime;
}

/* Selects every fourth element
   among any group of siblings */
:nth-child(4n) {
  color: lime;
}

Code Example 4

li:nth-child(odd) { /* Selects only odd elements */
    color: green;   
}

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