Sass lint error

_grid-blocks.scss

// Styles that affect all .grid-blocks
.grid-block {
  height: 0;
  padding-bottom: 50%;
  position: relative;
  overflow: hidden;

  .fill-space {
    @include fill-space;
  }

  .content-block {
    @include fill-space; // If a url is provided, fill space with a.content-block
  }

  .block-content { // Inner wrapper with padding applied
    @include fill-space;
    padding: $grid-block-padding;

    @include cinema-up {
      padding: $grid-block-padding;
    }

    @include tablet {
      padding: $grid-block-padding-tablet;
    }

    @include mobile {
      padding: $grid-block-padding-mobile;
    }
  }

  &:hover,
  &:focus {
    @include tile-hover;
  }

  &:active {
    @include tile-hover;
  }
}

// Styles for Quotes
.quote {

  ._text {
    padding: 40px;
    right: 0;
    left: 0;
    max-width: 900px; // just for quotes right now, may become global/reusable
    margin: 0 auto;
  }

  ._quote {
    font-size: 36px;
    line-height: (56 / 36);
    margin: 0 0 50px 0;
    color: $indigo-900; //temporary

    @include cinema-up {
      font-size: 36px;
      line-height: (56 / 36);
    }

    @include tablet {
      font-size: 24px;
      line-height: (40 / 24);
    }

    @include mobile {
      font-size: 24px;
      line-height: (40 / 24);
      margin: 0 0 30px 0;
    }
  }

  ._attribution {
    font-size: 16px;
    color: $indigo-900; //temporary

    @include cinema-up {
      font-size: 16px;
      line-height: (22 / 16);
    }

    @include tablet {
      font-size: 16px;
      line-height: (22 / 16);
    }

    @include mobile {
      font-size: 16px;
      line-height: (22 / 16);
    }
  }
}

// Styles for Articles
.article {

  background: #1de9b6; // Temporary

  ._text {
    @include vertical-align;
    background: #ccc;

    .title-lockup {
      background: #ececec;

      .title {
        font-size: 36px;
        line-height: (44 / 36);
      }

      .description {
        font-size: 16px;
        line-height: (19 / 16);
        margin-top: 5px;
      }
    }

    .author-lockup {

      .byline {
        display: table;
      }

      .avatar {
        display: block;
        border-radius: 40px;
        float: left;
        height: 40px;
        width: 40px;
        margin-right: 16px;
        overflow: hidden;

        img {
          width: 100%;
          height: auto;
        }
      }

      .authorname {
        display: table-cell;
        vertical-align: middle;
      }
    }

    @include mobile {
      //@include fill-space;
      //@include remove-vertical-align;
    }
  }
}