_color.sass

$pink: #F781F3
$grey: #A4A4A4

main.css.sass

@import 'helper/colors'
@import 'base/typography'

body
  background-color: white

.navbar
  width: 100%
  height: 40px
  text-align: center
  position: absolute
  top: 0
  left: 0
  background-color: pink

  .nav
    display: inline-block

.header
  height: 30%
  padding: 25px

.wrapper
  width: 100%

.products
  text-align: center
  background-color: green

  .product
    width: 20%
    height: 25%
    display: inline-block
    margin: 10px 15px
    background-color: white
    text-align: left


    img
      max-width: 100%

en la linea 14 y 28 las variables debes llamarlas con el signo $ 👍