documize/gui/app/styles/core/widget/widget-symbol.scss

.symbol {
    display: inline-block;
    border-radius: 2px;
    height: 40px;
    width: 40px;
    padding: 0;
    line-height: 0;
    margin: 0;
    text-align: center;
	background-color: map-get($gray-shades, 300);

    > .material-icons {
        font-size: 22px;
        margin-top: 20px;
        color: map-get($gray-shades, 600);
    }
}