styles.css

.mapboxgl-style-list
{
    display: none;
}

.mapboxgl-ctrl-group .mapboxgl-style-list button
{
    background: none;
    border: none;
    cursor: pointer;
    display: block;
    font-size: 14px;
    padding: 8px 8px 6px;
    text-align: right;
    width: 100%;
    height: auto;
}

.mapboxgl-style-list button.active
{
    font-weight: bold;
}

.mapboxgl-style-list button:hover
{
    background-color: rgba(0, 0, 0, 0.05);
}

.mapboxgl-style-list button + button
{
    border-top: 1px solid #ddd;
}

.mapboxgl-style-switcher
{ 
    background-image: url(data:image/svg+xml;base64,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);
    background-position: center;
    background-repeat: no-repeat;
    background-size: 70%;
}