style.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style-type: none;
    text-decoration: none;
    ;
}

body {
    background: rgb(230, 230, 230);
}

.header {
    display: flex;
    position: relative;
}

.header .sidebar {
    position: fixed;
    width: 200px;
    height: 100%;
    background: rgb(6, 5, 61);
}

.sidebar .item h1 {
    background: rgb(250, 205, 3);
    color: #fff;
    text-align: center;
    padding: 10px;
    margin-bottom: 0;
}

.sidebar li {
    margin-top: 2px;
    padding: 15px;
    color: grey;
    position: inherit;
}

.elemnts {
    border-left: 1px solid transparent;
}

.elemnts .icons {
    width: 25px;
    color: rgb(250, 205, 3);
}

.elemnts:hover {
    cursor: pointer;
    color: rgb(250, 205, 3);
    border-left-color: rgb(250, 205, 3);
    background: rgb(36, 36, 75);
}

.top {
    width: 100%-200px;
    margin-left: 200px;
    position: -webkit-sticky;
    position: sticky;
    top: 0;
    z-index: 1;
}

.top .header1 {
    padding: 15px;
    background: rgb(255, 255, 255);
    color: rgb(56, 55, 55);
    text-align: center;
    margin-bottom: 0;
}