html,
body {
    height: 100%;
    margin: 0;
}
.leaflet-container {
    height: 1000px;
    width: 1200px;
    max-width: 100%;
    max-height: 100%;
}
#map {
    width: 1400px;
    height: 800px;
    margin-left: auto;
    margin-right: auto;
}