// avoid text selection
@mixin not-selectable-text() {
    /* Firefox all */
    -moz-user-select: none;
    /* IE 10+ */
    -ms-user-select: none;
    /* Chrome all / Safari all */
    -webkit-user-select: none;
    /* Likely future */
    user-select: none;
}

// use for retina background images @1x / @2x / @3x
@mixin image-retina($filename, $extension) {

    background-image: url($filename + '.' + $extension);

    @media  (-webkit-min-device-pixel-ratio: 2),
            (-moz-min-device-pixel-ratio: 2),
            (min-resolution: 192dpi),
            (min-resolution: 2dppx) {
        & {
            background-image: url($filename + '@2x.' + $extension);
        }
    }

    @media  (-webkit-min-device-pixel-ratio: 3),
            (-moz-min-device-pixel-ratio: 3),
            (min-resolution: 288dpi),
            (min-resolution: 3dppx) {
        & {
            background-image: url($filename + '@3x.' + $extension);
        }
    }

}

// placeholder color
@mixin placeholder-color($color) {
    &::-webkit-input-placeholder {
        /* WebKit browsers */
        color: $color !important;
        opacity: 1 !important;
    }
    &:-moz-placeholder {
        /* Mozilla Firefox 4 to 18 */
        color: $color !important;
        opacity: 1 !important;
    }
    &::-moz-placeholder {
        /* Mozilla Firefox 19+ */
        color: $color !important;
        opacity: 1 !important;
    }
    &:-ms-input-placeholder {
        /* Internet Explorer 10+ */
        color: $color !important;
        opacity: 1 !important;
    }
}

// placeholder font size
@mixin placeholder-font-size($font-size) {
    &::-webkit-input-placeholder {
        /* WebKit browsers */
        font-size: $font-size !important;
    }
    &:-moz-placeholder {
        /* Mozilla Firefox 4 to 18 */
        font-size: $font-size !important;
    }
    &::-moz-placeholder {
        /* Mozilla Firefox 19+ */
        font-size: $font-size !important;
    }
    &:-ms-input-placeholder {
        /* Internet Explorer 10+ */
        font-size: $font-size !important;
    }
}

// placeholder font style
@mixin placeholder-font-style($font-style) {
    &::-webkit-input-placeholder {
        /* WebKit browsers */
        font-style: $font-style !important;
    }
    &:-moz-placeholder {
        /* Mozilla Firefox 4 to 18 */
        font-style: $font-style !important;
    }
    &::-moz-placeholder {
        /* Mozilla Firefox 19+ */
        font-style: $font-style !important;
    }
    &:-ms-input-placeholder {
        /* Internet Explorer 10+ */
        font-style: $font-style !important;
    }
}