@mixin border-radius($topleft: 0, $topright: 0, $bottomright: 0, $bottomleft: 0) {
    @if $topleft == 0 and $topright == 0 and $bottomright == 0 and $bottomleft == 0 {
        border-radius: 0;
    } @else if $topleft == 0px and $topright == 0px and $bottomright == 0px and $bottomleft == 0px {
        border-radius: 0;
    } @else {
        border-radius: $topleft $topright $bottomright $bottomleft;
    }
}

@mixin box-shadow($value) {
    box-shadow: $value;
}

@mixin background($from, $to) {
    @if $to == $from {
        background: $to;
    } @else {
        background: $to;
        background: linear-gradient(to bottom, $from, $to);
        filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#{ie_hex_str($from)}', endColorstr='#{ie_hex_str($to)}');
    }
}

@mixin border($top, $left, $right, $bottom, $color) {
    @if $top == 0px and $left == 0px and $right == 0px and $bottom == 0px {
        border: 0;
    } @else {
        border-top: $top solid $color;
        border-left: $left solid $color;
        border-right: $right solid $color;
        border-bottom: $bottom solid $color;
    }
}

@mixin mobile {
    @media only screen and (max-width : $responsive_breakpoint) {
        @content;
    }
}

@mixin desktop {
    @media only screen and (min-width : $responsive_breakpoint + 1) {
        @content;
    }
}