.side-bar{
   
    background: #6c757d;
    width: 210px;
    height: 100vh;
    position: fixed;
    top: 60px;
    left: 0;
    overflow-y: auto;
    transition: all 0.5s ease;
}

header{
    background: #34495e;
    padding: 15px;
    text-align: center;
}
header img{
    width: 50px;
    margin-bottom: 2px;
    border-radius: 50%;
}

.menu .item{
    position: relative;
}
.menu .item a, .menu .item .sub-btn {
    color: #fff;
    padding: 10px 20px;
    text-decoration: none;
    display: block;
    border-bottom: 1px solid #3d5a75;
    transition: all 0.4s ease;
}
.menu .item a:hover, .menu .item .sub-btn:hover{
    background-color: #34495e;
}

.sub-menu{
    display: none;
    background: #3d5a75;
}

.sub-item{
    padding-left: 40px;
}

.dropdown{
    float: right;
    transition: all 0.4s ease;
}

.rotate{
    transform: rotate(90deg);
}