anchor.diff:                                  overflow-y scroll
                               .col
                                   padding 0.8rem
  -                                .upload-block
  +                                .room-block
                                       position relative
                                       height 8rem
                                       width 8rem
                                       border-radius 3px
  -                                .upload-block
  -                                    > i
  -                                        transition 0.6s ease-out
  -                                        cursor pointer
  -                                        display none
  +                                .room-block
                                       > div
                                           transition 0.6s ease-out
                                           position absolute
                                           width 100%
  -                                        height 1.6rem
  +                                        height 2rem
  +                                        line-height: 2rem
                                           bottom 0
                                           display none
                                           background #FFFFFF
                                           opacity 0.5
  -                                        > div
  -                                            display none
  -                                            margin 0
  -                                            margin-top 0.6rem
  -                                .upload-block:hover
  -                                    > i
  -                                        display block
  +                                        cursor pointer
  +                                        p
  +                                            margin 0 auto
  +                                            text-align:center
  +                                .room-block:hover
                                       > div
                                           display block
                       .user
  
positive.code:     script.
          (function () {
              $('.slider').slider({full_width: true,interval:3000,indicators:false})
          })()
  
negative.code:                             div.row
                                  -for(var i=0;i<25;i++)
                                      div.col
                                          div.room-block.hoverable.grey.lighten-3
                                              div
                                                  p 进入房间
              div.col.l3.m3.s4
                  div.card-panel.white.user
                      div.row
  