.sidebar
{
    width: 300px;
    height: fit-content;    

    flex-shrink: 0;

    margin-top: 2px;

    margin-left: 2px;
    margin-right: .2em;    

    padding: 18px;

    background: #faf7ef;

    border: 1px solid #d7ccb6;

    border-radius: 12px;

    box-shadow:
        5px 5px 6px rgba(0,0,0,.5),
        inset 0 1px 0 rgba(255,255,255,.8);
}
.sidebar-title
{
    margin: 0 0 18px;

    text-align: center;

    font-family: Georgia, serif;

    font-size: 2rem;

    color: #00267f; 

    border-bottom: 1px solid #d8c8ae;

    padding-bottom: 10px;
}
.lesson-menu details
{
    margin-bottom: 14px;
}
.lesson-menu summary
{
    padding: 10px 12px;

    border-radius: 8px;

    background: #efe5d2;

    color: #5d4632;

    font-weight: bold;

    cursor: pointer;

    transition: .2s;
}
.lesson-menu summary:hover
{
    background: #e6d7bc;
}
.lesson-menu a
{
    display: block;

    padding: 7px 10px;

    border-radius: 6px;

    color: #3d4f8c;

    text-decoration: none;

    transition: .15s;
}
.lesson-menu a:hover
{
    background: #eef4ff;
}
.lesson-menu ul
{
    list-style: none;

    margin: 8px 0 0 18px;

    padding: 0;
}

.lesson-menu li
{
    margin: 5px 0;
}

.lesson-menu a.current
{
    display: block;

    background: linear-gradient(#de9639, #d58420);

    color: white;

    font-weight: bold;


    border-radius: 6px;

    box-shadow:
        inset 0 1px 1px rgba(255,255,255,.35),
        0 1px 3px rgba(0,0,0,.15);
}