_sass/core/includes/highlights-three-columns-band.scss

.highlights-three-columns-band {
  .highlight-columns-block {
    img ~ .block-title {
      background-color: $blue;
      padding: 1rem;
      margin-top: -3px;
      h2 {
        color: $white;
        margin: 0;
      }
    }
  }
}