message: Minor fixes on styles of <Loader />
diff: & > &__spinner {
  position: absolute;
  - left: 50%;
  - transform: translate(-50%, -50%);
  }
  & > &__spinner.fixed {
  }
  &__spinner {
  - width: rem($base-size);
  - height: rem($base-size);
  + width: rem(#{$base-size});
  + height: rem(#{$base-size});
  border-radius: 50%;
  transition-property: transform;
  &--small {
  border: 2px solid $grey-500;
  border-top: 2px solid $primary-color;
  - width: rem(15px);
  - height: rem(15px);
  - top: calc(50% - 5px);
  + width: rem(#{$base-size / 2});
  + height: rem(#{$base-size / 2});
  + top: calc(50% - #{$base-size / 4});
  }
  &--middle {
  border: 2px solid $grey-500;
  border-top: 2px solid $primary-color;
  - width: rem(20px);
  - height: rem(20px);
  - top: calc(50% - 10px);
  + width: rem(#{$base-size - $gutter-size});
  + height: rem(#{$base-size - $gutter-size});
  + top: calc(50% - #{($base-size - $gutter-size) / 2});
  + left: calc(50% - #{($base-size - $gutter-size) / 2});
  }
  &--regular {
  border: 6px solid $grey-500;
  border-top: 6px solid $primary-color;
  - width: rem(60px);
  - height: rem(60px);
  - top: calc(50% - 20px);
  + width: rem(#{$base-size * 2});
  + height: rem(#{$base-size * 2});
  + top: calc(50% - #{$base-size});
  + left: calc(50% - #{$base-size});
  }
  }
  }
  