styles.css

.fullscreen-icon { background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABoAAAAaCAQAAAADQ4RFAAAAUklEQVR4AWOgGhgF/8HwPIrYeYgoIU0OKGIOxGm6jyJ2n5Cm8wwOQEUGKGIGQBEHoAwB0AA0FwEbSAgOBBwWmggHBOVBTjhyKU9GhBMslcAoAABPu2Hh6JIyeQAAAABJRU5ErkJggg==); }
.leaflet-retina .fullscreen-icon { background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADQAAAA0CAQAAABvcdNgAAAAnklEQVR4Ae2WVQEDMRAFn4RIi8OVtBIiIQ7KzO3dlN+8z4MJbEDGGPPXTA+SukQevTlKlCq6RFFSor7RXFR1qkehawTRo9uqIOaoPyTqQ0Wporh76GJdFg+zqbS4odm8s6nAkVQ1Tc+kqQqkano5pKpdFTVhTG8EwyKLwPLmF+xHbkH8psofEx918PFHOX85+YbrFn+B5K/Ef4wxxswAnU97CHDaZQMAAAAASUVORK5CYII=); background-size: 26px 26px; }
.leaflet-container:-webkit-full-screen { width: 100% !important; height: 100% !important; z-index: 99999; }
.leaflet-container:-ms-fullscreen { width: 100% !important; height: 100% !important; z-index: 99999; }
.leaflet-container:full-screen { width: 100% !important; height: 100% !important; z-index: 99999; }
.leaflet-container:fullscreen { width: 100% !important; height: 100% !important; z-index: 99999; }
.leaflet-pseudo-fullscreen { position: fixed !important; width: 100% !important; height: 100% !important; top: 0px !important; left: 0px !important; z-index: 99999; }