.presentation__sidebar {
    /*box*/
    position:sticky;
    top:60px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    height:calc(100vh - 60px);
    width:260px;
    padding:20px 15px 15px 15px;
    overflow-y:auto;
}

/*--------------------------------------------------------------------------*\
        scrollbar
\*--------------------------------------------------------------------------*/

.presentation__sidebar::-webkit-scrollbar {
    /*box*/
    width: 6.5px;

    /*background*/
    background-size: 6.5px;
    background: var(--c-tertiary-4);
}

.presentation__sidebar::-webkit-scrollbar-thumb {
    /*background*/
    background-color: var(--c-primary-4);

    /*border*/
    border-radius: 2px
}

.presentation__sidebar::-webkit-scrollbar-thumb:hover {
    /*background*/
    background-color: var(--c-primary-3);
}