div#1 with position:relative
z-index: 5
div#2 with position: absolute
z-index: auto
div#4 with position: relative;
z-index: 6
div#5 with position: absolute;
z-index: 3
div#6 with position: relative;
z-index: 2
div#7 with position: relative;
z-index: -1
div#3 with position:relative
z-index: 2
Использование свойства z-index для #div2

auto   Изменение opacity: 1