/* transition */
@mixin transition($property){
    -webkit-transition: $property;
        transition: $property;
}

/* flex */
@mixin flex($property){
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    align-items: center
}

/* transform */
@mixin transform($property) {
  -webkit-transform: $property;
      -ms-transform: $property;
          transform: $property;
}


/* opacity */
@mixin opacity($opacity){
    opacity: $opacity;
    -ms-filter: $opacity;
}