qwc2/components/style/FullscreenSwitcher.css

QGIS Web Client

div.FullScreenSwitcher {
    display: inline-block;
    height: 100%;
    cursor: pointer;
    width: 1em;
    margin-left: -1em;
}

div.FullScreenSwitcher > span {
    display: inline-block;
    vertical-align: top;
    width: 0;
    height: 0;
    border-style: solid;
}

div.FullScreenSwitcher > span.maximize {
    border-width: 0 1em 1em 0;
    border-color: transparent var(--panel-text-color) transparent transparent;
}

div.FullScreenSwitcher > span.minimize {
    border-width: 1em 0 0 1em;
    border-color: transparent transparent transparent var(--panel-text-color);
}