L.Control.ZoomBox.css

.leaflet-zoom-box-control {
    font-size: 18px;
}
.leaflet-zoom-box-crosshair {
    cursor: crosshair !important;
}
.leaflet-zoom-box-icon {
    background: transparent no-repeat center center;
    /*src: https://design.google.com/icons/#ic_crop_free*/
    background-image: url(data:image/svg+xml;base64,PHN2ZyBmaWxsPSIjMDAwMDAwIiBoZWlnaHQ9IjI0IiB2aWV3Qm94PSIwIDAgMjQgMjQiIHdpZHRoPSIyNCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4gICAgPHBhdGggZD0iTTAgMGgyNHYyNEgweiIgZmlsbD0ibm9uZSIvPiAgICA8cGF0aCBkPSJNMyA1djRoMlY1aDRWM0g1Yy0xLjEgMC0yIC45LTIgMnptMiAxMEgzdjRjMCAxLjEuOSAyIDIgMmg0di0ySDV2LTR6bTE0IDRoLTR2Mmg0YzEuMSAwIDItLjkgMi0ydi00aC0ydjR6bTAtMTZoLTR2Mmg0djRoMlY1YzAtMS4xLS45LTItMi0yeiIvPjwvc3ZnPg==);
}
.leaflet-zoom-box-icon.active {
    color: #FFF;
    background-color: #CCC;
    /*src: https://design.google.com/icons/#ic_center_focus_strong*/
    background-image: url(data:image/svg+xml;base64,PHN2ZyBmaWxsPSIjMDAwMDAwIiBoZWlnaHQ9IjI0IiB2aWV3Qm94PSIwIDAgMjQgMjQiIHdpZHRoPSIyNCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4gICAgPHBhdGggZD0iTTAgMGgyNHYyNEgweiIgZmlsbD0ibm9uZSIvPiAgICA8cGF0aCBkPSJNMTIgOGMtMi4yMSAwLTQgMS43OS00IDRzMS43OSA0IDQgNCA0LTEuNzkgNC00LTEuNzktNC00LTR6bS03IDdIM3Y0YzAgMS4xLjkgMiAyIDJoNHYtMkg1di00ek01IDVoNFYzSDVjLTEuMSAwLTIgLjktMiAydjRoMlY1em0xNC0yaC00djJoNHY0aDJWNWMwLTEuMS0uOS0yLTItMnptMCAxNmgtNHYyaDRjMS4xIDAgMi0uOSAyLTJ2LTRoLTJ2NHoiLz48L3N2Zz4=);
}
.leaflet-zoom-box-icon.leaflet-disabled{
    background-image: url(data:image/svg+xml;base64,PHN2ZyBmaWxsPSIjQkJCQkJCIiBoZWlnaHQ9IjI0IiB2aWV3Qm94PSIwIDAgMjQgMjQiIHdpZHRoPSIyNCIgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4gICAgPHBhdGggZD0iTTAgMGgyNHYyNEgweiIgZmlsbD0ibm9uZSIvPiAgICA8cGF0aCBkPSJNMyA1djRoMlY1aDRWM0g1Yy0xLjEgMC0yIC45LTIgMnptMiAxMEgzdjRjMCAxLjEuOSAyIDIgMmg0di0ySDV2LTR6bTE0IDRoLTR2Mmg0YzEuMSAwIDItLjkgMi0ydi00aC0ydjR6bTAtMTZoLTR2Mmg0djRoMlY1YzAtMS4xLS45LTItMi0yeiIvPjwvc3ZnPg==);
}