css for adding bar at the bottom of slides

[SoumayaMauthoorMOJ]

I'm creating a custom theme. Is there a way to add a bar or box at the bottom of slides without passing in an image? Similar to this theme , but at the bottom instead of at the top?

[yhatt]

section {
  box-shadow: inset 0 -10px 0 red;
}

Show the example at JSFiddle...

[SoumayaMauthoorMOJ]

Thank you!