code-lab/node_modules/vuetify/lib/labs/VStepperVertical/_variables.scss

$stepper-vertical-item-transition-duration: .2s !default;
$stepper-vertical-item-transition-property: opacity !default;
$stepper-vertical-item-transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1) !default;