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

/***********************
 ! Check and Radio items
************************/

$suffix: if($variant == "dark", "-dark", "");

@mixin toggle($type) {
    background-image: none;

    -gtk-icon-source: url("../assets/#{$type}-unchecked#{$suffix}.png");

    &:disabled { -gtk-icon-source: url("../assets/#{$type}-unchecked-insensitive#{$suffix}.png"); }

    &:checked, &:active {
        -gtk-icon-source: url("../assets/#{$type}-checked#{$suffix}.png");

        &:disabled { -gtk-icon-source: url("../assets/#{$type}-checked-insensitive#{$suffix}.png"); }
    }

    &:indeterminate {
        -gtk-icon-source: url("../assets/#{$type}-mixed#{$suffix}.png");

        &:disabled { -gtk-icon-source: url("../assets/#{$type}-mixed-insensitive#{$suffix}.png"); }
    }

    menuitem &, modelbutton & {
        -gtk-icon-source: url("../assets/menuitem-#{$type}-checked-insensitive.png");

        &:disabled { -gtk-icon-source: none; }

        &:checked, &:active {
            -gtk-icon-source: url("../assets/menuitem-#{$type}-checked.png");

            &:hover { -gtk-icon-source: url("../assets/menuitem-#{$type}-checked-hover.png"); }

            &:disabled { -gtk-icon-source: url("../assets/menuitem-#{$type}-checked-insensitive.png"); }
        }

        &:indeterminate {
            -gtk-icon-source: url("../assets/menuitem-#{$type}-mixed.png");

            &:hover { -gtk-icon-source: url("../assets/menuitem-#{$type}-mixed-hover.png"); }

            &:disabled { -gtk-icon-source: url("../assets/menuitem-#{$type}-mixed-insensitive.png"); }
        }
    }
}

@include exports("checkradio") {
    radio {
        @include toggle("radio");
        min-width: 16px;
        min-height: 16px;
    }

    check {
        @include toggle("checkbox");
        min-width: 16px;
        min-height: 16px;
    }

    iconview.content-view.cell.check {
        -gtk-icon-source: url("assets/grid-selection-unchecked#{$suffix}.png");

        &:active { -gtk-icon-source: url("assets/grid-selection-checked#{$suffix}.png"); }
    }
}


/********
 ! Switch
*********/

@include exports("switch") {
    switch {
        border-radius: $roundness;
        padding: $spacing;
        border: none;
        outline: none;
        transition: all 0.4s linear;
        transition: background-color 0.3s linear;
        min-width: 93px;
        min-height: 25px;
        background-color: $switch_bg_color;
        color: $switch_fg_color;

        slider {
            background-color: $switch_slider_bg_color;
            transition: all 0.3s linear;
            box-shadow: 0px 1px 3px 0px rgba(0, 0, 0, 0.1);
            border-radius: $roundness;
        }

        &:checked {
            background-color: $selected_bg_color;
            background-image: none;
            border-color: $selected_bg_color;
            color: $base_color;

            slider {
                background-color: $white;
            }
        }

        &:disabled {
            background-color: $switch_disabled_bg_color;
            background-image: none;
            border-color: $switch_disabled_border_color;
            color: $switch_disabled_fg_color;

            slider {
                background-color: $switch_disabled_slider_bg_color;
            }
        }
    }
}