.app-button {
  display: inline-block;
  font-size: 1em;
  line-height: 1em;
  background: transparent;
  margin: 0;
  padding: 0.25em;
  border: 0;
  outline: 0;
  cursor: pointer;
  vertical-align: middle;
  border-radius: 4px;
  transition: all 0.1s ease-out;
  color: #999;
}

.app-button:hover {
  color: #000;
}

.app-button:active {
  transform: translate(0, 1px);
  color: #000;
  background: #f3f3f3;
}

.app-button:focus {
  color: #000;
}

.app-button.-circle {
  width: 1.5em;
  height: 1.5em;
  border-radius: 50%;
}

.app-button.-xl {
  font-size: 1.5em;
}

@media (min-width: 600px) {
  .app-button.-xl {
    font-size: 2em;
  }
}