/**
  * @stylesheet button-groups.less Button Groups
  * @parent styles-base 2
  *
  * @description
  * Group a series of buttons together on a single line with the button group.
  * Add on optional JavaScript radio and checkbox style behavior with our buttons plugin.
  *
  * #### Tooltips & popovers in button groups require special setting
  * When using tooltips or popovers on elements within a `.btn-group`, you'll
  * have to specify the option container: 'body' to avoid unwanted side effects
  * (such as the element growing wider and/or losing its rounded corners when
  * the tooltip or popover is triggered).
  *
  * #### Ensure correct role and provide a label
  * In order for assistive technologies – such as screen readers – to convey
  * that a series of buttons is grouped, an appropriate role attribute needs to
  * be provided. For button groups, this would be `role="group"`, while toolbars
  * should have a `role="toolbar".
  *
  * One exception are groups which only contain a single control (for instance
  * the justified button groups with `<button>` elements) or a dropdown.
  *
  * In addition, groups and toolbars should be given an explicit label, as most
  * assistive technologies will otherwise not announce them, despite the presence
  * of the correct role attribute. In the examples provided here, we use aria-label,
  * but alternatives such as aria-labelled by can also be used.
  **/
  /**
  @styles button-groups-basic-example
  @parent button-groups.less 0
  * ## Basic Example
  * Wrap a series of buttons with `.btn` in `.btn-group`.
  * @demo demos/button-groups/basic-example/demo.html
  **/
  /**
  @styles button-groups-toolbar
  @parent button-groups.less 1
  * ## Button Toolbar
  * Combine sets of `<div class="btn-group">` into a `<div class="btn-toolbar">`
  * for more complex components.
  * @demo demos/button-groups/button-toolbar/demo.html
  **/
  /**
  @styles button-groups-sizing
    @parent button-groups.less 2
  * ## Sizing
  * Instead of applying button sizing classes to every button in a group,
  * just add `.btn-group-*` to each `.btn-group`, including when nesting multiple groups.
  * @demo demos/button-groups/sizing/demo.html
  **/
  /**
  @styles button-groups-vertical
    @parent button-groups.less 4
  * ## Vertical Variation
  * Make a set of buttons appear vertically stacked rather than horizontally.
  *
  * @demo demos/button-groups/vertical/demo.html
  **/
  /**
  @styles button-groups-justified
    @parent button-groups.less 5
  * ## Justified button groups
  * Make a group of buttons stretch at equal sizes to span the entire width of
  * its parent. Also works with button dropdowns within the button group.
  *
  * ##### Handling borders
  * Due to the specific HTML and CSS used to justify buttons
  * (namely `display: table-cell`), the borders between them are doubled. In
  * regular button groups, `margin-left: -1px` is used to stack the borders instead
  * of removing them. However, margin doesn't work with `display: table-cell`.
  * As a result, depending on your customizations to Bootstrap, you may wish to
  * remove or re-color the borders.
  * ##### IE8 and borders
  * Internet Explorer 8 doesn't render borders on buttons in a justified button group,
  * whether it's on `<a>` or `<button>` elements. To get around that, wrap each
  * button in another `.btn-group`.
  *
  * ##### With `<a>` Elements
  * Just wrap a series of `.btns` in `.btn-group.btn-group-justified`.
  *
  * @demo demos/button-groups/justified/demo.html
  *
  * ##### Links acting as buttons
  * If the `<a>` elements are used to act as buttons – triggering in-page
  * functionality, rather than navigating to another document or section within
  * the current page – they should also be given an appropriate `role="button"`.
  **/
  /**
  @styles button-groups-justified-elements
  @parent button-groups.less 6
  * #### With `<button>` Elements
  * To use justified button groups with `<button>` elements, you must wrap each
  * button in a button group. Most browsers don't properly apply our CSS for
  * justification to `<button>` elements, but since we support button dropdowns,
  * we can work around that.
  * @demo demos/button-groups/justified-buttons-elements/demo.html
  **/
  /**
  @styles button-groups-nesting
    @parent button-groups.less 7
  * ## Dropdown Menus within Buttons
  * Place a `.btn-group` within another `.btn-group` when you want dropdown menus
  * mixed with a series of buttons.
  *
  * The interaction is handled by `dropdown.js` which is not included in the style guide. 
  * The javascript adds a class `.open` to the parent `.btn-group` class allowing the 
  * `.dropdown-menu` class to display.
  * @demo demos/button-groups/nesting/demo.html
  **/