Answers for "nth child every second element"

nth-child(2n+1)

/* Select the first list item */
li:nth-child(1) { }

/* Select the 5th list item */
li:nth-child(5) { }

/* Select every other list item starting with first */
li:nth-child(odd) { }

/* Select every 3rd list item starting with first */
li:nth-child(3n) { }

/* Select every 3rd list item starting with 2nd */
li:nth-child(3n - 1) { }

/* Select every 3rd child item, as long as it has class "el" */
.el:nth-child(3) { }

get second child div css

.manufacturer_box div:nth-child(2) {
            border-top: 5px solid #e0e0e0 !important; 
     }