Retrospring/app/assets/stylesheets/components/_inbox-entry.scss

.inbox-entry {
  &--new {
    box-shadow: 0 0.125rem 0.25rem var(--primary);

    .card-header {
      background-color: var(--primary);
      color: RGB(var(--primary-text));

      .text-muted {
        color: RGBA(var(--primary-text), 0.8) !important;
      }
    }
  }
}