.collapsible {
    cursor: pointer;
    position: relative;
    padding-right: 25px; /* space for the icon */
}

.collapsible::after {
    content: '\002B'; /* Plus sign */
    font-weight: bold;
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
}

.collapsible.active::after {
    content: '\2212'; /* Minus sign */
}

.collapsible-content {
    display: none;
    padding-left: 1rem;
    border-left: 1px solid #4a5568; /* A subtle line to show nesting */
    margin-left: 0.5rem;
    margin-top: 0.5rem;
}