Which blue background? If you are using the native gauges available in Super Tiles, the standard dashboard theming / styling can be applied to the tiles background color (even making it transparent and disabling the shadow if you want the gauge to visually appear standalone)
If I remember correctly, the community released Gauge Custom Tiles pass the standard tile background through as well, so same concept applies there with styling the underlying tile itself to achieve the look you’re after (including transparent).