core/less/components-dir/_side-nav.less
.sidebar {
  #side-menu {
    visibility: hidden;
  }
  
  ul li {
    border-bottom: 1px solid darken(@gray-lightest, 6.5%);
    a {
      &.active {
        background-color: @gray-lighter;
      }
    }
  }

  .sidebar-nav.navbar-collapse {
    padding-left: 0;
    padding-right: 0;
  }

  .sidebar-search {
    padding: 15px;
  }

  .arrow {
    float: right;

    &.iconfont:before {
      content: "\e608";
    }
  }

  .active > a > .iconfont.arrow:before {
    content: "\e607";
  }

  .nav-second-level li, .nav-third-level li {
    border-bottom: none !important;
  }

  .nav-second-level li a {
    padding-left: 37px;
  }

  .nav-third-level li a {
    padding-left: 52px;
  }
}

@media(min-width:768px) {   //PC端
  .sidebar {
    z-index: 1;
    position: absolute;
    width: 250px;
    top: @top-bar-height + @top-bar-boder-width;
    bottom: 0;
    overflow-y: auto;
  }

  .navbar-top-links .dropdown-messages,
  .navbar-top-links .dropdown-tasks,
  .navbar-top-links .dropdown-alerts {
    margin-left: auto;
  }
}