gnome-shell/data/theme/gnome-shell-sass/widgets/_popovers.scss

/* Popovers/Menus */

// the popover itself
.popup-menu-boxpointer {
  margin: $base_margin; // used as distance from the screen edge
}

// container of the popover menu
.popup-menu {
  min-width: 15em;
  color: $fg_color;

  //.popup-status-menu-item {font-weight: normal;  color: pink;} //dunno what that is
  &.panel-menu {
    -boxpointer-gap: $base_margin+2px; // distance from the panel
    margin-bottom: 1.75em; // so it doesn't touch the bottom of the screen
  }
}

// popover content
.popup-menu-content {
  padding: $base_padding;
  // account for margin oddities
  padding-top: $base_padding - 2px !important;
  padding-bottom: $base_padding - 2px !important;
  border-radius: $modal_radius - 2px;
  border: 1px solid $borders_edge;
  box-shadow: 0 2px 4px 0 rgba(0,0,0,0.1);
  background-color: $bg_color;
}

// menu items
.popup-menu-item {
  padding: $base_padding*1.5 $base_padding*2;
  margin: 2px 0;
  border-radius: $base_border_radius;
  transition: 0.2s all ease;
  background-color: transparent;

  &:focus, &:hover {
   background-color: $hover_bg_color !important;
   &:active { background-color: $active_bg_color !important;}
 }

  &:checked {background-color: $checked_bg_color !important;}

  &:checked {
    margin-bottom: 0;
    box-shadow: inset 0 -1px 0 0 darken($checked_bg_color, 5%);
    border-radius: $base_border_radius $base_border_radius 0 0;
    &:focus,&:hover { background-color: lighten($checked_bg_color, 3%) !important;}
    &:active { background-color: lighten($checked_bg_color, 5%) !important;}
  }

  &:active {
    background-color: lighten($active_bg_color, 5%);
    color: $active_fg_color;
  }

  &:insensitive {color: transparentize($fg_color,0.5);}
}


// all other graphical elements (sliders)
.popup-inactive-menu-item {
  color: $fg_color;
  &:insensitive { color: $insensitive_fg_color; }
}

// symbolic icons in popover
.popup-menu-arrow,
.popup-menu-icon {
  icon-size: 16px !important; // for some reason the variable doesn't work here
}

.popup-menu-arrow {
  &:ltr {margin-right: $base_margin;}
  &:rtl {margin-left: $base_margin;}
}


// popover submenus
.popup-sub-menu {
  background-color: $checked_bg_color;
  border-radius: 0 0 $base_border_radius $base_border_radius;

  .popup-menu-ornament {
    min-width: $base_icon_size !important;
  }

  // submenu specific styles
  .popup-menu-item {
    border-radius: 0;
    margin: 0;

    &:last-child {
      border-radius: 0 0 $base_border_radius $base_border_radius;
    }

    &:focus,&:hover { background-color: lighten($hover_bg_color, 10%) !important;}
    &:checked {
      background-color: lighten($checked_bg_color, 10%) !important;
      &:focus,&:hover { background-color: lighten($checked_bg_color, 8%) !important;}
    }
    &:active { background-color: lighten($active_bg_color, 10%) !important;}
  }

  .popup-menu-section {
    .popup-menu-item:last-child {
      &:hover,&:focus {border-radius: 0;}
    }
    &:last-child .popup-menu-item:last-child {
      border-radius: 0 0 $base_border_radius $base_border_radius;
    }
  }
}

// container for radio and check boxes
.popup-menu-ornament {
  @extend %heading;
  width: 1.2em;
  text-align: center !important;

  &:ltr {text-align: right;};
  &:rtl {text-align: left;};
}

// separator
.popup-separator-menu-item {
  padding:0;
  margin: 4px 0;

  .popup-separator-menu-item-separator {
    height: 1px; //not really the whole box
    background-color: $borders_color;
  }

  .popup-menu-ornament {
    width: 0 !important;
  }

  .popup-sub-menu & {
    padding: 0;
    margin-right: 2.5em !important; // account for ornament
    background-color: transparent;

    .popup-separator-menu-item-separator {
      background-color: lighten($borders_color, 7%);
    }
  }
}

// desktop background menu
.background-menu {
  -boxpointer-gap: $base_margin;
  -arrow-rise: 0px; // hide the beak on the menu
}

// system status menu
.aggregate-menu {
  min-width: 22em;

  // this is unneeded at the top-level in this menu, hide it
  .popup-menu-ornament { width: 0 !important; }

  // lock screen, shutdown, etc. buttons
  .popup-menu-icon {
    -st-icon-style: symbolic;
    &:ltr {margin-right: $base_margin*2;}
    &:rtl {margin-left: $base_margin*2;}
  }

  // account for ornaments in submenus with padding
  .popup-sub-menu .popup-menu-item > :first-child {
    // this value is hardcoded for visual effect
    &:ltr { margin-left: $base_margin*2;}
    &:rtl { margin-right: $base_margin*2;}
  }
}

// right-click (and panel) app menu
.app-menu {
  max-width: 27.25em;
  .popup-menu-content { margin: $base_margin;}

  &.panel-menu {
    .popup-menu-content { margin: 0;} // avoid doubling up margin
  }

  // this is unneeded at the top-level in this menu, hide it
  .popup-menu-ornament { width: 0 !important; }

  .popup-inactive-menu-item:first-child {
    // "Open Windows" label
    > StLabel {
      @extend %caption_heading;
      &:ltr {margin-right: $base_margin*2;}
      &:rtl {margin-left: $base_margin*2;}
    }
  }
}