//声明变量
$onewidth:100px;
//声明混合宏
@mixin tow{
  width: 100px;
  height: 100px;
  background-color:aqua;
  border: 1px solid orange;
}
//调用混合宏
.box2{
  @include tow;
}
.box2{
  @include  tow;
}
//声明一个带参数的混合宏
@mixin ouba($kk){
  margin-bottom: $kk;
}
//调用一个带参数的混合宏
.box1{
  @include ouba(20px);
}
.box2{
  @include ouba(50px);
}
//扩展、继承 关键词@extend
.haha{
    outline: none;
  border: 1px solid royalblue;
  padding-bottom: 12px;
}
//调用继承样式
input[type="text"]{
  @extend .haha;
  color: aqua;
}
input[type="password"]{
  @extend .haha;
  color: pink;
}
//占位符
%xixi{
  width: 500px;
  height: 200px;
  background-color: salmon;
}
//使用占位符
.box3{
  @extend %xixi;
}
//调用声明
.box1{
  width: $onewidth;
  height: $onewidth;
  background-color: olive;
}
//属性嵌套
.box1{
  border:{
    top: 2px solid black;
    left: 2px solid red ;
    bottom: 2px solid pink;
    right: 2px solid lawngreen;
  };
  margin: {
    top: 8px;
    bottom: 5px;
    right: 10px;
    left: 10px;
  };
}