.flex {
  display: -webkit-box;
  /* 老版本语法: Safari, iOS, Android browser, older WebKit browsers. */
  display: -moz-box;
  /* 老版本语法: Firefox (buggy) */
  display: -ms-flexbox;
  /* 混合版本语法: IE 10 */
  display: -webkit-flex;
  /* 新版本语法: Chrome 21+ */
  display: flex;
  /* 新版本语法: Opera 12.1, Firefox 22+ */
}

.flex-1 {
  -webkit-flex: 1;
  /* Chrome */
  -ms-flex: 1;
  /* IE 10 */
  flex: 1;
  /* NEW, Spec - Opera 12.1, Firefox 20+ */
  -webkit-box-flex: 1;
  /* OLD - iOS 6-, Safari 3.1-6 */
  -moz-box-flex: 1;
  /* OLD - Firefox 19- */
}

.flex-2 {
  -webkit-flex: 2;
  /* Chrome */
  -ms-flex: 2;
  /* IE 10 */
  flex: 2;
  /* NEW, Spec - Opera 12.1, Firefox 20+ */
  -webkit-box-flex: 2;
  /* OLD - iOS 6-, Safari 3.1-6 */
  -moz-box-flex: 2;
  /* OLD - Firefox 19- */
}

.flex-4 {
  -webkit-flex: 4;
  /* Chrome */
  -ms-flex: 4;
  /* IE 10 */
  flex: 4;
  /* NEW, Spec - Opera 12.1, Firefox 20+ */
  -webkit-box-flex: 4;
  /* OLD - iOS 6-, Safari 3.1-6 */
  -moz-box-flex: 4;
  /* OLD - Firefox 19- */
}

.flex-v {
  -webkit-box-orient: vertical;
  -webkit-flex-direction: column;
  -ms-flex-direction: column;
  flex-direction: column;
}

.flex-wrap {
  -moz-box-lines: multiple;
  -webkit-box-lines: multiple;
  -o-box-lines: multiple;
  box-lines: multiple;
  -webkit-flex-wrap: wrap;
  flex-wrap: wrap;
}

.flex-align-center {
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
}

.flex-pack-center {
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}

.flex-pack-justify {
  -webkit-box-pack: justify;
  -webkit-justify-content: space-between;
  -ms-flex-pack: justify;
  justify-content: space-between;
}

.flex-pack-around {
  -webkit-box-pack: center;
  -webkit-justify-content: space-around;
  -ms-flex-pack: center;
  justify-content: space-around;
}

.flex-align-justify {
  -webkit-align-content: space-between;
  align-content: space-between;
}

.flex-align-around {
  -webkit-align-content: space-around;
  align-content: space-around;
}