numix-gtk-theme/gtk-3.0/scss/widgets/_button.scss

/*********
 ! Buttons
**********/

@include exports("button_extends") {
	%button {
		padding: ($spacing - 1px) ($spacing + 1px);
		border-width: 1px;
		border-style: solid;
		border-radius: $roundness;
		transition: 100ms ease;
		outline-color: transparent;

		-GtkWidget-focus-padding: 1;
		-GtkWidget-focus-line-width: 0;
	}

	%linked_button {
		border-width: 1px;
		border-style: solid;
		border-radius: 0;
		border-right-style: none;
		border-left-style: none;

		&:first-child {
			border-width: 1px;
			border-radius: $roundness;
			border-left-style: solid;
			border-right-style: none;
			border-top-right-radius: 0;
			border-bottom-right-radius: 0;

			&:dir(rtl) {
				border-left-style: none;
				border-right-style: solid;
			}
		}

		&:last-child {
			border-width: 1px;
			border-radius: $roundness;
			border-left-style: none;
			border-right-style: solid;
			border-top-left-radius: 0;
			border-bottom-left-radius: 0;

			&:dir(rtl) {
				border-left-style: solid;
				border-right-style: none;
			}
		}

		&:only-child, &:first-child:only-child {
			border-width: 1px;
			border-style: solid;
			border-radius: $roundness;
		}
	}
}

@mixin linked_button($bg) {
	@extend %linked_button;

	box-shadow: inset -1px 0 border_normal($bg),
				0 1px 2px -1px alpha($dark_shadow, .3);

	&:focus, &:hover {
		box-shadow: inset -1px 0 border_focus($bg),
					0 1px 2px -1px alpha($dark_shadow, .3);
	}

	&:active, &:active:hover,
	&:active:focus, &:active:hover:focus,
	&:checked, &:checked:hover,
	&:checked:focus, &:checked:hover:focus {
		box-shadow: inset -1px 0 border_active($bg),
					inset 1px 0 alpha($dark_shadow, .07),
					inset 0 1px alpha($dark_shadow, .08),
					inset 0 -1px alpha($dark_shadow, .05);
	}

	&:insensitive { box-shadow: inset -1px 0 border_insensitive($bg); }

	&:last-child, &:only-child,
	&:insensitive:last-child, &:insensitive:only-child,
	&:active:insensitive:last-child, &:active:insensitive:only-child,
	&:checked:insensitive:last-child, &:checked:insensitive:only-child { box-shadow: none; }

	&:active:last-child, &:active:only-child,
	&:active:last-child:focus, &:active:only-child:focus,
	&:active:last-child:hover, &:active:only-child:hover,
	&:active:last-child:hover:focus, &:active:only-child:hover:focus,
	&:checked:last-child, &:checked:only-child,
	&:checked:last-child:focus, &:checked:only-child:focus,
	&:checked:last-child:hover, &:checked:only-child:hover,
	&:checked:last-child:hover:focus, &:checked:only-child:hover:focus {
		box-shadow: inset 1px 0 alpha($dark_shadow, .07),
					inset 0 1px alpha($dark_shadow, .08),
					inset -1px 0 alpha($dark_shadow, .07);
	}
}

@mixin button($bg, $fg) {
	@include linear-gradient(shade($bg, 1.05));
	@extend %button;

	color: $fg;
	box-shadow: 0 1px 2px -1px alpha($dark_shadow, .3);

	&:insensitive {
		@include linear-gradient(shade($bg, .95));

		color: mix($bg, $fg, .5);
		box-shadow: none;
	}

	&, &.flat {
		@include border(shade($bg, 1.05));

		&:focus, &:hover {
			@include linear-gradient(shade($bg, 1.1));

			box-shadow: 0 1px 3px -1px alpha($dark_shadow, .5);
		}

		&:checked, &:active {
			@include linear-gradient(shade($bg, .95));

			box-shadow: inset 1px 0 alpha($dark_shadow, .07),
						inset 0 1px alpha($dark_shadow, .08),
						inset -1px 0 alpha($dark_shadow, .07),
						inset 0 -1px alpha($dark_shadow, .05);
		}

		&:active:insensitive,
		&:checked:insensitive {
			@include linear-gradient(shade($bg, .8));

			box-shadow: none;
		}
	}

	&.flat {
		color: inherit;
		border-color: transparent;
		background-color: transparent;
		background-image: none;
		box-shadow: none;
	}

	&.separator, .separator {
		border: 1px solid currentColor;
		color: shade($bg, ($contrast + .05));

		&:insensitive { color: shade($bg, .85); }
	}
}

@include exports("button") {
	%close_button {
		border: 1px solid transparent;
		background-color: transparent;
		background-image: none;
		box-shadow: none;

		&:focus, &:hover {
			border: 1px solid alpha(black, 0.3);
			background-color: alpha(white, 0.2);
			background-image: none;
			box-shadow: none;
		}

		&:active, &:checked, &:active:hover, &:checked:hover  {
			border: 1px solid alpha(black, 0.3);
			background-color: alpha(black, 0.1);
			background-image: none;
			box-shadow: none;
		}
	}

	.button {
		@include button($bg_color, $fg_color);

		&.default { @include button($selected_bg_color, $selected_fg_color); }

		&.linked, .linked & { @include linked_button($bg_color); }

		.spinbutton & {
			color: mix($text_color, $base_color, 0.4);
			padding: $spacing ($spacing * 2);
			border: none;
			border-radius: 0;
			border-style: none;
			background-color: transparent;
			background-image: none;
			box-shadow: inset 1px 0 shade($base_color, 0.9);

			&:insensitive {
				color: mix($text_color, $base_color, 0.7);
				box-shadow: inset 1px 0 shade($base_color, 0.85);
			}

			&:active, &:checked, &:hover { color: $text_color; }

			&:first-child {
				border-radius: $roundness 0 0 $roundness;
				box-shadow: none;
			}

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

			&:dir(rtl) { box-shadow: inset -1px 0 shade($base_color, 0.9); }
		}

		.spinbutton.vertical & {
			border: 1px solid shade($bg_color, 0.8);
			border-radius: $roundness;
			background-color: shade($bg_color, 1.08);
			background-image: none;
			color: $fg_color;
			box-shadow: none;

			&:hover {
				border-color: shade($bg_color, 0.7);
				background-color: shade($bg_color, 1.10);
				background-image: none;
			}

			&:active, &:checked {
				border-color: shade($bg_color, 0.8);
				background-color: shade($bg_color, 0.95);
				background-image: none;
			}

			&:active:hover, &:checked:hover {
				border-color: shade($bg_color, 0.7);
			}

			&:focus, &:hover:focus, &:active:focus, &:active:hover:focus { border-color: shade($bg_color, 0.7); }

			&:insensitive {
				border-color: shade($bg_color, 0.85);
				background-color: shade($bg_color, 0.9);
				background-image: none;
			}

			&:first-child {
				border-width: 1px;
				border-bottom-width: 0;
				border-bottom-right-radius: 0;
				border-bottom-left-radius: 0;
			}

			&:last-child {
				border-width: 1px;
				border-top-width: 0;
				border-top-left-radius: 0;
				border-top-right-radius: 0;
			}
		}

		.spinbutton.vertical.entry {
			border-width: 1px;
			border-style: solid;
			border-radius: 0;
		}
	}
}