You can set width of the stepper component to the fixed width the smaller content's width.

.stepper {
  width: 100%;
  max-width: 600px;
}

If you want stepper head to be the minimum size but content to fill all the space, then set stepper to the fixed with of the head section, set its head to visible, and the content's position to absolute like so:

.stepper {
  width: 360px;
  overflow: visible;
}

.stepper-content {
  position: absolute;
  width: 100vw !important;
}

Here is the snippet: https://mdbootstrap.com/snippets/standard/m-duszak/3661729#css-tab-view