message: style(CalloutData): fixed source text width
  The source text should fit 90% of 640px width, this change fix that issue.
diff: &__source {
  @include carbon--type-style('body-short-01', true);
  + width: 90%;
  + max-width: carbon--mini-units(80);
  padding-bottom: $layout-03;
  @include carbon--breakpoint('md') {
  