$zindex-active: 1
$zindex-hover: 2
$zindex-focus: 3
$zindex-multi: 4
$zindex-dropdown: 1000
$zindex-sticky: 1020
$zindex-fixed: 1030
$zindex-modal-backdrop: 1040
$zindex-modal: 1050
$zindex-popover: 1060
$zindex-tooltip: 1070
$zindex-stretched-link: 1