numix-gtk-theme/gtk-3.20/scss/widgets/_button.scss

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

@include exports("button_extends") {
    %button {
        padding: $spacing ($spacing + 2px);
        border-width: 1px;
        border-style: solid;
        border-radius: $roundness;
        transition: 150ms ease;
        outline-color: transparent;
    }

    %linked_middle {
        border-radius: 0;
        border-left-style: none;
        border-right-style: solid;

        &:dir(rtl) {
            border-radius: 0; // needed when including %linked_middle:dir(rtl)
            border-right-style: none;
            border-left-style: solid;
        }
    }

    %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) {
    $border_strength: if(lightness($bg) > 50, 0, .1);
    $shadow_strength: if(lightness($bg) > 50, 0, .1);

    @extend %linked_button;

    box-shadow: inset -1px 0 border_normal(rgba(0, 0, 0, .12 + $border_strength)),
    0 1px 2px -1px alpha($dark_shadow, .12 + $shadow_strength);

    &:focus, &:hover {
        box-shadow: inset -1px 0 border_focus(rgba(0, 0, 0, .12 + $border_strength)),
        0 1px 2px -1px alpha($dark_shadow, .32 + $shadow_strength);
    }

    &:active, &:active:hover,
    &:active:focus, &:active:hover:focus,
    &:checked, &:checked:hover,
    &:checked:focus, &:checked:hover:focus {
        box-shadow: inset -1px 0 border_active(rgba(0, 0, 0, .12 + $border_strength)),
        inset 0 1px alpha($dark_shadow, .07),
        inset 0 -1px alpha($dark_shadow, .05);
    }

    &:disabled { box-shadow: inset -1px 0 shade($bg, .8); }

    &:last-child, &:only-child { box-shadow: 0 1px 2px -1px alpha($dark_shadow, .12 + $shadow_strength); }

    &:last-child:hover, &:only-child:hover { box-shadow: 0 1px 2px -1px alpha($dark_shadow, .32 + $shadow_strength); }

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

    &:active:last-child, &:active:last-child:focus, &:active:last-child:hover, &:active:last-child:hover:focus,
    &:checked:last-child, &:checked:last-child:focus, &:checked:last-child:hover, &:checked:last-child:hover:focus {
        box-shadow: inset 0 1px alpha($dark_shadow, .07),
        inset -1px 0 alpha($dark_shadow, .06);
    }

    &:active:only-child, &:active:only-child:focus, &:active:only-child:hover, &:active:only-child:hover:focus,
    &:checked:only-child, &:checked:only-child:focus, &:checked:only-child:hover, &:checked:only-child:hover:focus {
        box-shadow: inset 1px 0 alpha($dark_shadow, .06),
        inset 0 1px alpha($dark_shadow, .07),
        inset -1px 0 alpha($dark_shadow, .06);
    }
}

@mixin button($bg, $fg) {
    $border_strength: if(lightness($bg) > 50, 0, .1);
    $shadow_strength: if(lightness($bg) > 50, 0, .1);

    $button_bg: if(hue($bg) == 0deg, shade($bg, 1.2), $bg);

    @extend %button;
    @include linear-gradient($button_bg);
    @include border(rgba(0, 0, 0, .12 + $border_strength));

    color: $fg;
    box-shadow: 0 1px 2px -1px alpha($dark_shadow, .12 + $shadow_strength);

    &.flat {
        border-color: alpha($button_bg, 0);
        background-color: alpha($button_bg, 0);
        background-image: none;
        box-shadow: none;
    }

    &, &.flat {
        &:focus, &:hover {
            @include linear-gradient(shade($button_bg, 1.2));
            @include border(rgba(0, 0, 0, .2 + $border_strength));

            box-shadow: 0 1px 2px -1px alpha($dark_shadow, .32 + $shadow_strength);
        }

        &:checked {
            @include linear-gradient(shade($button_bg, .7), to top);

            color: $white;
            box-shadow: inset 1px 0 alpha($dark_shadow, .06),
            inset 0 1px alpha($dark_shadow, .07),
            inset -1px 0 alpha($dark_shadow, .06),
            inset 0 -1px alpha($dark_shadow, .05);

            &:focus, &:hover {
                @include linear-gradient(shade($button_bg, .65), to top);

                color: $white;
            }
        }

        &:focus, &:hover { color: $fg; }

        &:active:disabled, &:checked:disabled {
            @include linear-gradient(shade($button_bg, .9));

            color: $fg;
            box-shadow: none;
        }

        &:disabled:disabled {
            @if (lightness($button_bg) > 50) {
                @include linear-gradient(shade($button_bg, .95));
            } @else {
                @include linear-gradient(alpha($button_bg, .3));
            }

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

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

        &:disabled { color: shade($button_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($black, .3);
            background-color: alpha($white, .2);
            background-image: none;
            box-shadow: none;
        }

        &:active, &:checked, &:active:hover, &:checked:hover {
            border: 1px solid alpha($black, .3);
            background-color: alpha($black, .1);
            background-image: none;
            box-shadow: none;
        }
    }

    button {
        min-height: 22px;
        min-width: 24px;
        @include button(shade($bg_color, 1.2), $fg_color);

        &.link, .link & { @include linked_button(shade($bg_color, 1.2)); }

        spinbutton & {
            color: mix($text_color, $base_color, .4);
            padding: $spacing ($spacing * 2);
            border: 0;
            border-radius: 0;
            border-style: none;
            background-color: transparent;
            background-image: none;
            box-shadow: inset 1px 0 shade($base_color, .9);

            &:disabled {
                color: mix($text_color, $base_color, .7);
                box-shadow: inset 1px 0 shade($base_color, .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, .9); }
        }

        spinbutton.vertical & {
            border: 1px solid shade($bg_color, .8);
            border-radius: $roundness;
            background-color: shade($bg_color, 1.08);
            background-image: none;
            color: $fg_color;
            box-shadow: none;

            &:hover {
                border-color: shade($bg_color, .7);
                background-color: shade($bg_color, 1.1);
                background-image: none;
            }

            &:active, &:checked {
                border-color: shade($bg_color, .8);
                background-color: shade($bg_color, .95);
                background-image: none;
            }

            &:active:hover, &:checked:hover {
                border-color: shade($bg_color, .7);
            }

            &:focus, &:hover:focus, &:active:focus, &:active:hover:focus { border-color: shade($bg_color, .7); }

            &:disabled {
                border-color: shade($bg_color, .85);
                background-color: shade($bg_color, .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;
        }

    }
}

/******************
! ComboBoxes *
*******************/

@include exports("combobox") {
    combobox {
        box button, box entry {
            @extend %linked_button;
            padding: ($spacing - 2px) ($spacing + 1px);
        }

        box > button {
            // the combo is a composite widget so the way we do button linked doesn't
            // work, special case needed. See
            // https://bugzilla.gnome.org/show_bug.cgi?id=733979
            &:dir(ltr) { @extend %linked_middle; }
            // specificity bump
            &:dir(rtl) { @extend %linked_middle:dir(rtl); }
        }

        &:first-child > button { @extend %linked_button:first-child; }

        &:last-child > button { @extend %linked_button:last-child; }

        &:only-child > button { @extend %linked_button:only-child; }
    }
}