//整个样式表中重复使用的样式

@mixin w_h($width:100%, $height:auto) {
  width: $width;
  height: $height;
}

@mixin flex($justify:space-between, $align:center) {
  display: flex;
  justify-content: $justify;
  align-items: $align;
}

@mixin position($type:relative, $top:auto, $bottom:auto, $left:auto, $right:auto, $zindex:0) {
  position: $type;
  top: $top;
  bottom: $bottom;
  left: $left;
  right: $right;
  z-index: $zindex;
}