.update-notes {
    width: min(100%, 640px);
    margin: 0 0 28px;
    padding: 20px 24px;
    border: 1px solid #454559;
    border-radius: 12px;
    background: #1c1c2b;
    color: #e2e2ec;
    text-align: left;
    line-height: 1.7;
}
.update-notes[hidden] { display: none; }
.update-notes h2 { margin: 0 0 12px; font-size: 16px; color: #fff; }
.update-notes ul { margin: 0; padding-left: 20px; }
.update-notes li + li { margin-top: 8px; }
.content-area { min-width: 0; overflow-y: auto; }
@media (max-width: 720px) {
    .sidebar { width: 112px; flex-shrink: 0; }
    .sidebar-item { padding: 14px 10px; font-size: 14px; letter-spacing: 0; }
    .content-area { padding: 24px 14px; }
    .selected-title { font-size: 24px; letter-spacing: 1px; }
    .update-notes { padding: 14px; font-size: 13px; }
}