Used so that semantic flow of document doesn't need to be flipped altering the sequence then using flex-flow: column-reverse on flex container.

.stack-page:nth-child(1) {z-index: 999;}
.stack-page:nth-child(2) {z-index: 998;}
.stack-page:nth-child(3) {z-index: 997;}
.stack-page:nth-child(4) {z-index: 996;}
.stack-page:nth-child(5) {z-index: 995;}
.stack-page:nth-child(6) {z-index: 994;}
.stack-page:nth-child(7) {z-index: 993;}
.stack-page:nth-child(8) {z-index: 992;}
.stack-page:nth-child(9) {z-index: 991;}
/* ... */
.stack-end {z-index: 1;}
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After
Edit in JS Bin