// d-flex prefixes
@mixin flex() {
	display: -webkit-box; 
	display: -moz-box;
	display: -ms-flexbox;
	display: -webkit-flex; 
	display: flex;
}

// transition
@mixin custom-transition($property,$duration) {
	-webkit-transition: $property $duration + s;
	-o-transition: $property $duration + s;
	transition: $property $duration + s
}