// Box
//
// A simple box style.
//
// A block is often styled as a box. However, this design component is
// not applied to any blocks by default; it is used as an example of how to
// build and document a CSS component.
//
// "box" is the name of our component, so we define a `.box` class that we can
// apply to any HTML element that needs the box styling. We also provide a
// `%box` placeholder selector so that we can easily extend the basic box
// component with `@extend %box;`.
//
// Take a look at the source code for this component for more information about
// building a good component.
//
// :hover - The hover/focus styling.
// .box--highlight - The "highlight" box variant.

.box,
%box {
  @include margin-bottom(1);
  border: 5px solid $border;
  padding: 1em;

  // Sass compiles this to the selector: .box__title, %box__title {}
  // The "__" (double underscore) is part of a BEM naming convention that
  // indicates the "title" is an _element_ of (a piece of) the "box" component.
  &__title {
    margin: 0;
  }

  // Sass compiles this nested ruleset's selector into:
  // .box:focus, .box:hover, .box.is-focus, .box--is-focus,
  // %box:focus, %box:hover, %box.is-focus, %box--is-focus {}
  //
  // The ".box--is-focus" class is a stray class we don't actually want, but we
  // deal with it because we often want a placeholder selector like
  // %box--is-focus in case we need to use @extends later.
  //
  // The ".is-" part of the class name is a Drupal 8 BEM naming convention that
  // indicates the "focus" is a _state_ of the "box" component.
  &:focus,
  &:hover,
  &.is-focus,
  &--is-focus {
    border-color: $text;
  }

  // Sass compiles this to the selector: .box--highlight, %box--highlight {}
  // The "--" (double dash) is part of a BEM naming convention that indicates
  // the "highlight" is a _modifier_, creating a new variation of the standard
  // "box" component.
  &--highlight {
    border-color: $link;
  }
}