.btn-pill class in LESS to include with Bootstrap's less files.

btn-pill.less

// Button styles
// -------------------------

// Pill button variants
.btn.btn-pill {

  // border-radius depends on button' height
  @border-radius-pill: (@font-size-base * @line-height-base + @padding-base-vertical * 2) / 2;
  border-radius: @border-radius-pill;

  // different for every button size
  &.btn-lg {
    @border-radius-pill: (@font-size-large * @line-height-large + @padding-large-vertical * 2) / 2;
    border-radius: @border-radius-pill;
  }
  &.btn-sm {
    @border-radius-pill: (@font-size-small * @line-height-small + @padding-small-vertical * 2) / 2;
    border-radius: @border-radius-pill;
  }
  &.btn-xs {
    @border-radius-pill: (@font-size-small * @line-height-small + @padding-xs-vertical * 2) / 2;
    border-radius: @border-radius-pill;
  }
}

pill styled button for bootstrap.md