Article element #1

position: relative;
z-index: 5;

Article Element #2

position: relative;
z-index: 2;

Section Element #4

position: relative;
z-index: 6;

Article Element #3

position: absolute;
z-index: 4;

Section Element #5

position: relative;
z-index: 1;

Section Element #6

position: absolute;
z-index: 3;