jellyfin-web/dashboard-ui/css/polymer/paper-icon-button-light.css

[is=paper-icon-button-light] {
    width: 40px;
    height: 40px;
    padding: 8px;
}
    [is=paper-icon-button-light] iron-icon {
        width: 100%;
        height: 100%;
    }

    [is=paper-icon-button-light] img {
        width: 100%;
        height: 100%;
    }

    [is=paper-icon-button-light] #background {
        transition: opacity .3s ease-out;
    }

    [is=paper-icon-button-light]:focus #background {
        background-color: currentcolor !important;
        opacity: .2 !important;
    }

    /* Make sure the img is on top of the ripple */
    [is=paper-icon-button-light] img {
        position: relative;
        z-index: 1;
    }