.left_menu{min-height:100%;width:200px;position:fixed;top:50px;left:0;bottom:0;background-color:#545c64;color:#fff;overflow-x:hidden;overflow-y:auto;transition:width .3s ease-in-out}.menu_mini{width:64px}.btn_collapse_div{position:absolute;color:#e8ecf0;left:0;right:0;bottom:0}.btn_collapse,.btn_collapse i{background:#0f1012}.btn_collapse i{display:block;cursor:pointer;transition:all .3s;padding:14px 16px;width:64px;text-align:center}.btn_collapse i:hover{color:#42aafa}