.atmosphere {
  background-image: url(images/bg.jpg);
  background-position: left;
  background-repeat: no-repeat;
  background-size: cover;
  opacity: 0.3;
}

.btn-primary {
  background-color:#cbff69; 
  padding: 20px;
}

#mail-btn {
  margin-top: 20px;
}



/* ══════════════════════════════════
   RESPONSIVE
   ══════════════════════════════════ */
   @media (max-width: 1024px) {
    #mail-btn {
      margin-left: 20px;
    }
  }
  
  @media (max-width: 768px) {
    #mail-btn {
      margin-left: 20px;
    }
  }
  
  @media (max-width: 624px) {
    #mail-btn {
      margin-left: 5px;
    }
  }

  @media (max-width: 420px) {
    #mail-btn {
      margin-left: 0px;
    }
  }