布局

组件布局包含了常用模块的组合

flex 类

.flex-center
  @flex
  @justify-center
  @align-center

.flex-center-justify
  @flex
  @justify-center

.flex-center-align
  @flex
  @align-center

其余类

.fixed-center  
  @fixed
.fixed-bottom
  @fixed  
  
.absolute-center
  @absolute
.absolute-bottom

# 布局