.navbar-header li {
    float: left;
    margin-left: 20px;
    margin-top: 10px;
    font-weight: bolder;
    font-size: 20px;
    list-style-type: none;
}

.left_bar {
    float:left;
    margin-top:50px;
   
}

.left_part {
     background-color:silver;
     min-height:450px;
}

.menu_li {
    list-style-type:none;
}

.menu_a {
    cursor:pointer;
    font-size:15px;
}