@mixin clearfix{
    zoom: 1;
    &:before,
    &:after {
        content: "";
        display: table;
    }
    &:after {
        clear: both;
        visibility: hidden;
        font-size: 0;
        height: 0;
    }
}
@mixin placeholder($color: $input-placeholder-color) {
    // Firefox
    &::-moz-placeholder {
        color: $color;
        opacity: 1; // Override Firefox's unusual default opacity; see https://github.com/twbs/bootstrap/pull/11526
    }
    // Internet Explorer 10+
    &:-ms-input-placeholder {
        color: $color;
    }
    // Safari and Chrome
    &::-webkit-input-placeholder {
        color: $color;
    }
}