postal/app/assets/stylesheets/application/elements/_button.scss

.button {
  display: inline-block;
  font: inherit;
  border-radius: 4px;
  appearance: none;
  background: $blue;
  color: #fff;
  font-size: 14px !important;
  margin: 0;
  vertical-align: top;
  padding: 6px 15px;
  border: 2px solid transparent;
  border-bottom: 2px solid darken($blue, 20%);

  &:active {
    background-color: darken($blue, 15%);
  }

  &:focus {
    border-color: darken($blue, 15%);
    background-color: lighten($blue, 5%);
  }

  &.is-spinning {
    color: transparent;
    background-repeat: no-repeat;
    background-position: center center;
    background-size: 25px;
    background-image: image-url('button-spinner.gif');
  }
}

.button--small {
  font-size: 12px !important;
  padding: 3px 10px;
  border-width: 1px;
}

.button--positive {
  background-color: $green;
  border-bottom-color: darken($green, 15%);

  &:active {
    background-color: darken($green, 15%);
  }

  &:focus {
    border-color: darken($green, 15%);
    background-color: lighten($green, 5%);
  }

  &.is-spinning {
    background-image: image-url('button-spinner-positive.gif');
  }

}


.button--neutral {
  background-color: #ccc;
  border-bottom-color: darken(#ccc, 15%);

  &:active {
    background-color: darken(#ccc, 15%);
  }

  &:focus {
    border-color: darken(#ccc, 15%);
    background-color: lighten(#ccc, 5%);
  }

  &.is-spinning {
    background-image: image-url('button-spinner-neutral.gif');
  }
}

.button--danger {
  background-color: $red;
  border-bottom-color: darken($red, 15%);

  &:active {
    background-color: darken($red, 15%);
  }

  &:focus {
    border-color: darken($red, 15%);
    background-color: lighten($red, 5%);
  }

  &.is-spinning {
    background-image: image-url('button-spinner-danger.gif');
  }
}

.button--dark {
  background-color: $darkBlue;
  border-bottom-color: darken($darkBlue, 15%);

  &:active {
    background-color: darken($darkBlue, 15%);
  }

  &:focus {
    border-color: darken($darkBlue, 15%);
    background-color: lighten($darkBlue, 5%);
  }

  &.is-spinning {
    background-image: image-url('button-spinner-dark.gif');
  }

}

.button--full {
  width: 100%;
  text-align: center;
}