.add {
  background: #282828;
  padding: 50px;
  font-size: 18px;
  color: #fff;
  border: none;
  border-radius: 300px;
  display: block;
  margin: auto;
  margin-top: 50px;
  padding-top: 10px;
  padding-bottom: 10px;
  margin-bottom: 50px;
}

.add:hover {
  background: #ffffff;
  padding: 50px;
  font-size: 18px;
  color: #000000;
  border: none;
  border-radius: 300px;
  display: block;
  margin: auto;
  margin-top: 50px;
  padding-top: 10px;
  padding-bottom: 10px;
  margin-bottom: 50px;
}

@media (min-width: 992px) {
  .your-class {
    margin-top: 50px;
  }
}

@media screen and (min-width: 992px) and (min-height: 580px) {
  .project-details {
    /*margin-top: 60px;*/
    margin-left: 50px;
  }
}