nav ul li {
    list-style-type: none;
    display: block;
    padding: 0;
    margin: 0;
}

#contents {
    display: flex;
    flex-direction: row;
}

#contents #sidebar {
    display: flex;
    flex-direction: column;
    width: 384px;
    min-height: 100vh;
    background-color: #C2C2C2;
    padding: 20px;
}

#contents #sidebar button:hover {
    cursor: pointer;
}

#contents #sidebar button:hover,
#contents #sidebar button:focus,
#contents #sidebar a:hover,
#contents #sidebar a:focus {
    background-color: #000000;
    color: #FFFFFF;
}

#contents #sidebar hr {
    background-color: #000000;
    width: 100%;
    height: 1px;
}

#contents main {
    display: flex;
    flex-direction: column;
    flex-grow: 1;
    padding: 20px;
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: #C2C2C2;
    color: #000000;
    text-decoration: none;
    text-align: center;
    border-radius: 5px;
    border: 1px solid #000000;
}

.btn-panel {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
    margin-bottom: 20px;
}