Z-Index

The .z-* classes are used to change the stack level of a certain element. Note that this will not work on elements with position static.

    <div class="container position-relative">
        <div class="z-3 position-absolute">
            .z-3
        </div>
        <div class="z-2 position-absolute">
            .z-2
        </div>
        <div class="z-1 position-absolute">
            .z-1
        </div>
        <div class="z-0 position-absolute">
            .z-0
        </div>
        <div class="z-n1 position-absolute">
            .z-n1
        </div>
    </div>