.btn-outline {
  color: inherit;
  background-color: transparent;
  transition: all .5s;
}
.btn-primary.btn-outline {
  color: #428bca;
}
.btn-success.btn-outline {
  color: #5cb85c;
}
.btn-info.btn-outline {
  color: #5bc0de;
}
.btn-warning.btn-outline {
  color: #f0ad4e;
}
.btn-danger.btn-outline {
  color: #bf6f6f;
}
.btn-primary.btn-outline:hover,
.btn-success.btn-outline:hover,
.btn-info.btn-outline:hover,
.btn-warning.btn-outline:hover,
.btn-danger.btn-outline:hover {
  color: white;
}