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

/* On-screen Keyboard */

$key_size: 1.2em;
$key_border_radius: $base_border_radius + 3px;
$key_bg_color:  $bg_color;
// $default_key_bg_color: darken($key_bg_color, 4%);
$default_key_bg_color: if($variant=='light', darken($osd_bg_color, 11%), lighten($osd_bg_color, 2%));


// draw keys using button function
%keyboard_key {
	@include button(normal, $c:$key_bg_color);

	&:focus { @include button(focus);}
	&:hover, &:checked { @include button(hover, $c: $key_bg_color);}
	&:active { @include button(active, $c: $key_bg_color); }
}

#keyboard {
	background-color: transparentize(if($variant=='light', darken($bg_color, 5%), darken($bg_color, 8%)), 0.1);
	box-shadow: inset 0 1px 0 0 $osd_outer_borders_color !important;

	.page-indicator {
		padding: $base_padding;

		.page-indicator-icon {
			width: 6px;
			height: 6px;
			&:checked {
				background-color:red;
			}
		}
	}
}

// the container for individual keys
.key-container {
	padding: $base_margin;
	spacing: $base_margin;
}

// the keys
.keyboard-key {
	@extend %keyboard_key;
	font-size: $base_font_size + 5pt;
	min-height: $key_size;
	min-width: $key_size;

	border-radius: $key_border_radius;

	&:grayed { //FIXMEy
		background-color: darken($bg_color, 3%);
		color: $osd_fg_color;
		border-color: $osd_borders_color;
	}

	// non-character keys
	&.default-key {

		// size of the icon asset
		background-size: 24px;

		@include button(normal, $c:$default_key_bg_color);
		&:hover, &:checked {@include button(hover, $c: $default_key_bg_color);}
		&:active { @include button(active, $c: $default_key_bg_color);}
		box-shadow: 0 1px 1px 0 rgba(0,0,0,0.1) !important; // drawing override because of a visual bug
	}

	// enter key is suggested-action
	&.enter-key {
		background-image: url("resource:///org/gnome/shell/theme/key-enter.svg");

		@include button(normal, $c:$selected_bg_color, $tc:$selected_fg_color);
		&:hover, &:checked { @include button(hover, $c: lighten($selected_bg_color, 3%));}
		&:active {@include button(active, $c: darken($selected_bg_color, 2%));}
		box-shadow: 0 1px 1px 0 rgba(0,0,0,0.1) !important; // drawing override because of a visual bug
	}

	// key assets
	&.shift-key-lowercase {background-image: url("resource:///org/gnome/shell/theme/key-shift.svg");}
	&.shift-key-uppercase {background-image: url("resource:///org/gnome/shell/theme/key-shift-uppercase.svg");}
	&.shift-key-uppercase:latched {background-image: url("resource:///org/gnome/shell/theme/key-shift-latched-uppercase.svg");}
	&.hide-key {background-image: url("resource:///org/gnome/shell/theme/key-hide.svg");}
	&.layout-key {background-image: url("resource:///org/gnome/shell/theme/key-layout.svg");}
}

// long press on a key popup
.keyboard-subkeys {
	color: $osd_fg_color;
	-arrow-border-radius: $modal_radius;
	-arrow-background-color: $osd_bg_color;
	-arrow-border-width: 1px;
	-arrow-border-color: lighten($osd_bg_color, 9%);
	-arrow-base: 20px;
	-arrow-rise: 10px;
	-boxpointer-gap: $base_spacing;

	.keyboard-key {
		@extend %keyboard_key;
		border-radius:$base_border_radius;
	}
}

// emoji
.emoji-page {
	.keyboard-key {
		background-color: transparent;
		border: none;
		color: initial;
	}
}

.emoji-panel {
	.keyboard-key:latched {
		border-color: lighten($selected_bg_color, 5%);
		background-color: $selected_bg_color;
	}
}

// suggestions
.word-suggestions {
	font-size: $base_font_size + 3pt;
	spacing: 12px;
	min-height: 20pt;
}