discourse/app/assets/stylesheets/common/components/buttons.scss

// --------------------------------------------------
// Buttons
// --------------------------------------------------

// Base
// --------------------------------------------------

@mixin btn(
  $text-color: var(--primary),
  $bg-color: var(--primary-low),
  $icon-color: var(--primary-high),
  $hover-text-color: var(--secondary),
  $hover-bg-color: var(--primary-medium),
  $hover-icon-color: var(--primary-low)
) {
  @include form-item-sizing;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  font-weight: normal;
  color: $text-color;
  &:visited {
    // covers cases where we add button classes to links
    color: $text-color;
  }
  background-color: $bg-color;
  background-image: linear-gradient(
    to bottom,
    rgba(0, 0, 0, 0),
    rgba(0, 0, 0, 0)
  );
  border-radius: var(--d-button-border-radius);
  transition: var(--d-button-transition);
  cursor: pointer;
  .d-icon {
    color: $icon-color;
    margin-right: 0.45em;
    transition: var(--d-button-transition);
    // For Windows High Contrast (see whcm.scss for more)
    @media (forced-colors: active) {
      color: ButtonText;
    }
  }
  .d-button-label + .d-icon {
    margin-left: 0.45em;
    margin-right: 0;
  }
  &.no-text {
    .d-icon {
      margin-right: 0;
    }
  }
  @include hover {
    background-color: $hover-bg-color;
    color: $hover-text-color;
    .d-icon {
      color: $hover-icon-color;
      // For Windows High Contrast (see whcm.scss for more)
      @media (forced-colors: active) {
        color: Highlight;
      }
    }
  }
  &:focus {
    outline: none;
    background-color: $hover-bg-color;
    color: $hover-text-color;
    .d-icon {
      color: $hover-icon-color;
      @media (forced-colors: active) {
        color: Highlight;
      }
    }

    &:focus-visible {
      @include darken-background($hover-bg-color, 0.1);
    }
  }

  .discourse-no-touch &:active:not(:hover):not(:focus),
  .discourse-no-touch &.btn-active:not(:hover):not(:focus),
  &:active:not(:hover):not(:focus),
  &.btn-active:not(:hover):not(:focus) {
    @include darken-background($bg-color, 0.6);
    color: $hover-text-color;
    .d-icon {
      color: $hover-icon-color;
    }
  }
  .discourse-no-touch &:active,
  .discourse-no-touch &.btn-active,
  &:active,
  &.btn-active {
    @include darken-background($bg-color, 0.3);
    color: $hover-text-color;
    .d-icon {
      color: $hover-icon-color;
    }
  }
  &[disabled],
  &.disabled {
    &:not(.is-loading) {
      opacity: 0.4;
    }
    &:hover {
      color: $text-color;
      background: $bg-color;
      .d-icon {
        color: $icon-color;
      }
    }
    cursor: not-allowed;
  }

  .loading-container {
    display: none;
    margin: 0 6.75px 0 0;
  }

  &.is-loading {
    &.btn-text {
      .d-button-label {
        font-size: var(--font-down-2);
      }

      &.btn-small {
        .loading-icon {
          font-size: var(--font-down-1);
          margin-right: 0.2em;
        }
      }
    }

    .loading-icon {
      animation: rotate-forever 1s infinite linear, fadein 1s;
    }
  }
}

.btn.hidden {
  display: none;
}

// Default button
// --------------------------------------------------

.btn {
  @include btn;
}

// Primary button
// --------------------------------------------------

.btn-primary {
  @include btn(
    $text-color: var(--secondary),
    $bg-color: var(--tertiary),
    $icon-color: var(--secondary),
    $hover-bg-color: var(--tertiary-hover),
    $hover-icon-color: var(--secondary)
  );
}

// Danger button
// --------------------------------------------------

.btn-danger {
  @include btn(
    $text-color: var(--secondary),
    $bg-color: var(--danger),
    $icon-color: var(--danger-low),
    $hover-bg-color: var(--danger-hover),
    $hover-icon-color: var(--danger-low)
  );
}

// ✘ and ✔ buttons
// --------------------------------------------------

.btn.cancel {
  @include btn(
    $text-color: var(--secondary),
    $bg-color: var(--danger),
    $icon-color: var(--secondary),
    $hover-bg-color: var(--danger-hover),
    $hover-icon-color: var(--secondary)
  );
}

.btn.ok {
  @include btn(
    $text-color: var(--secondary),
    $bg-color: var(--success),
    $icon-color: var(--secondary),
    $hover-bg-color: var(--success-hover),
    $hover-icon-color: var(--secondary)
  );
}

// Social buttons
// --------------------------------------------------

.btn-social {
  color: #000;
  background: #fff;
  border: 1px solid transparent;
  border-radius: var(--d-border-radius);
  &:hover,
  &:focus {
    box-shadow: var(--shadow-card);
    outline: 1px solid #000;
  }
  &[href] {
    color: var(--secondary);
  }
  &:before {
    margin-right: 9px;
    font-size: var(--font-0);
  }
  .d-icon,
  &.btn:hover .d-icon {
    color: #000;
  }
  &.google_oauth2 {
    background: var(--google);
    color: #333;
    // non-FA SVG icon for Google in login-buttons.hbs
    .d-icon {
      opacity: 0.9;
    }
    &:hover,
    &:focus {
      color: inherit;
    }
  }

  &.cas {
    .d-icon {
      color: var(--cas);
    }
    &:hover {
      .d-icon {
        color: var(--cas);
      }
    }
  }
  &.twitter {
    .d-icon {
      color: var(--twitter);
    }
    &:hover {
      .d-icon {
        color: var(--twitter);
      }
    }
  }
  &.github {
    .d-icon {
      color: var(--github);
    }
    &:hover {
      .d-icon {
        color: var(--github);
      }
    }
  }
  &.discord {
    .d-icon {
      color: var(--discord);
    }
    &:hover {
      .d-icon {
        color: var(--discord);
      }
    }
  }
  // https://developers.facebook.com/docs/facebook-login/userexperience/#buttondesign
  // if you are unable to use Facebook blue, revert to black and white.
}

// Button Sizes
// --------------------------------------------------

// Small

.btn-small {
  font-size: var(--font-down-1);
  min-height: 20px;
}

// Large

.btn-large {
  font-size: var(--font-up-1);
}

// Bonus Buttons
// --------------------------------------------------

.btn-flat {
  background: transparent;
  border: 0;
  line-height: var(--line-height-small);
  transition: var(--d-button-transition);
  .d-icon {
    color: var(--primary-low-mid);
    transition: var(--d-button-transition);
  }
  .discourse-no-touch & {
    &:hover,
    &:focus {
      color: var(--primary);
      .d-icon {
        color: var(--primary);
      }
    }
    &:hover {
      background: transparent;
    }
    &:focus {
      background: var(--primary-low);
    }
  }
  &.close {
    background: transparent;
    font-size: var(--font-up-2);
    .d-icon {
      color: var(--primary-high);
    }
    .discourse-no-touch & {
      &:hover,
      &:focus {
        background: transparent;
        .d-icon {
          color: var(--primary);
        }
      }
    }
    &:focus {
      background: transparent;
      .d-icon {
        color: var(--primary);
      }
    }
  }
  &.btn-text {
    color: var(--tertiary);
    &[disabled] {
      &,
      &:hover,
      &.btn-hover,
      &:focus {
        color: var(--primary);
      }
    }
    &:not([disabled]) {
      &:hover,
      &.btn-hover,
      &:focus {
        color: var(--tertiary-hover);
      }

      &:active,
      &.btn-active {
        @include darken-background(transparent, 0.2);
      }
    }
  }
  &:focus {
    outline: none;
    background: var(--primary-low);
    .d-icon {
      color: var(--primary);
    }
  }
  &.back-button {
    margin-bottom: 1em;
  }
}

.btn-link {
  background: transparent;
  border: 0;
  padding: 0;
  color: var(--tertiary);
  .discourse-no-touch & {
    &:hover {
      color: var(--tertiary);
      background: transparent;
    }
  }
  &:focus {
    color: var(--tertiary);
    background: transparent;
  }
  &:focus-visible {
    color: var(--tertiary);
    background: transparent;
    @include default-focus;
  }
}

@mixin btn-colors($btn-color) {
  color: var(--#{$btn-color});
  .d-icon {
    color: inherit;
  }
  &:focus,
  &:focus-visible {
    color: var(--#{$btn-color}-hover);
  }
  .discourse-no-touch & {
    &:hover {
      color: var(--#{$btn-color}-hover);
    }
  }
}

.btn-transparent {
  &,
  &.btn-default {
    background: transparent !important;
    border: 0;
    color: var(--primary);
    .d-icon {
      color: var(--primary-high);
    }
    &:focus,
    &:focus-visible {
      color: var(--tertiary-hover);
      .d-icon {
        color: inherit;
      }
    }
    .discourse-no-touch & {
      &:hover {
        color: var(--tertiary-hover);
        .d-icon {
          color: inherit;
        }
      }
    }
  }
  &.btn-primary {
    @include btn-colors("tertiary");
  }
  &.btn-danger {
    @include btn-colors("danger");
  }
  &.btn-success {
    @include btn-colors("success");
  }
}

.btn-mini-toggle {
  border-radius: var(--d-border-radius);
  padding: 0.4em 0.467em;
  .d-icon {
    color: var(--primary-medium);
  }
  @include hover {
    .d-icon {
      color: var(--primary);
    }
  }
}