.hero {
  background-image: url('../images/hero-mobile.png');
}

@media (min-width: 768px) {
  .hero {
    background-image: url('../images/hero-desktop.png');
  }
}

.hero.about-hero { background-image: url('../images/about-team.png'); }
.hero.services-hero { background-image: url('../images/service-overview.png'); }
.hero.septic-hero { background-image: url('../images/service-overview.png'); } /* fallback since septic-hero.png not generated */
.hero.contact-hero { background-image: url('../images/trusted-partner.png'); }