LiveReload error

// LiveReload error 

ParseError: Syntax Error on line 74 in /Users/louhuang/Dropbox/GitHub/rclosner/lv-dof/public/less/styles.less:74:2
73 .left-screen {
74   &:extend(.full-screen);
75   .box-shadow(3px 0 6px rgba(0,0,0,0.10));

// LESS contents
// ...

.full-screen {
  .transition(width .8s);
  width: 100%;
  min-height: 100%;
  z-index: @ui-index;
  padding: 30px;
  background-color: @background;
  position: relative;
  overflow-x: hidden;
  overflow-y: auto;
} 

.left-screen {
  &:extend(.full-screen);
  .box-shadow(3px 0 6px rgba(0,0,0,0.10));
  width: @section-part-width;
  border-right: 1px solid @lightgray;

  header {
    margin-left: 120px;
    #logo {
      left: 100px;
    } 
  }

  footer {
    width: @section-part-width - (30 * 2);
  }

  #pi {
    right: 0; 
  }

  .container {
    width: 100%;  
  }
}

// ...