MediaWiki:Collapse.css

/* Minimal collapsible blocks */
.mw-collapsible {
    margin: 0.3em 0;
    border: 1px solid #a2a9b1;
    background-color: #f8f9fa;
    border-radius: 2px;
}

.mw-collapsible-toggle {
    font-weight: bold;
    padding: 0.4em 0.6em;
    cursor: pointer;
    color: #202122;
    background-color: #eaecf0;
    border-bottom: 1px solid #c8ccd1;
    position: relative;
    padding-right: 1.5em; /* Space for arrow */
}

.mw-collapsible-toggle:hover {
    background-color: #e0e2e6;
}

/* Pure CSS arrow indicator */
.mw-collapsible-toggle:after {
    content: "";
    position: absolute;
    right: 0.6em;
    top: 50%;
    transform: translateY(-50%);
    width: 0;
    height: 0;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-top: 5px solid #54595d;
    transition: transform 0.2s ease;
}

.mw-collapsed .mw-collapsible-toggle:after {
    transform: translateY(-50%) rotate(-90deg);
}

.mw-collapsible-content {
    padding: 0.6em 0.8em;
    background-color: #ffffff;
}

.mw-collapsed .mw-collapsible-content {
    display: none;
}