.sidebar-nav li {
    position: relative;
    padding-left: 1.1em;
}
.sidebar-nav li::before {
    content: '➤';
    position: absolute;
    left: 0;
    color: #505d6b;
    font-size: 0.9em;
    transition: transform 0.2s ease;
}
.sidebar-nav li.open::before {
    content: '➤';
    transform: rotate(90deg);
}