Backgrounds - Gradient

Colors we use for backgrounds.

Example
Horizontal
Vertical
Radial
Demos: [Horizontal](https://webslides.tv/demos/classes#slide=29) [Vertical](https://webslides.tv/demos/classes#slide=32) [Radial](https://webslides.tv/demos/classes#slide=31)
Markup 
  <div class="bg-gradient-h">Horizontal</div>
  <div class="bg-gradient-v">Vertical</div>
  <div class="bg-gradient-r">Radial</div>
Demos:
[Horizontal](https://webslides.tv/demos/classes#slide=29)
[Vertical](https://webslides.tv/demos/classes#slide=32)
[Radial](https://webslides.tv/demos/classes#slide=31)
Source: _color.scss, line 201