Addition of Fronts
It wouold be incredibly useful to add the layer of "fronts" into the layers palet.
Fronts are NOT drawn by numerical weather forecast models, but by skill weather forecast meteorologists.
As Windy shows maps directly and automatically issued from weather forecast models, there is no way to show fronts.
In addition, what brings the plot of fronts? The position of the air masses? The changes of direction, and the eventual strengthening, of the wind? The type of weather, cloud systems, precipitation? All of this you find it in detail on Windy. The fronts were imagined in the 1930s, at the time when this synthetic and graphic presentation allowed a simplified representation of current and forecasted weather. Today's weather models provide much more detailed forecasts, even if they are not able to offer drawings of fronts.
Personnaly, I use to look at Temperature layer at 850hPa which gives a rough idea of the location of the different fronts...
To add to @idefix37 fronts are sometimes unmistakeable phenomena, but sometimes a bit vague and sometimes very vague. There may be a single front or there may be several lesser fronts succession, or just a weather change over a period of an hour or two to cooler temperature and a different wind vector.
There'a judgement and even a psychological component to what constitutes a front. A human forecaster will take the human impact into account in choosing whether to draw a front, how far it extends horizontally and when it has degraded sufficiently to drop it. It's a tough job for a NWP model - more of a neural problem - but expect it one day.
It's probably better to look at rain, temperature and wind change then decide if that's what you call a front.
I agree with idefix: temperature layer at 850hPa is useful. Looking at winds also helps: wind abruptly changes direction by maybe 45 degrees at the front. Over ocean, surface winds are fine, but over land I'd look at winds at 850-900hPA as well. It also helps to look at precipitation: it rains there. It also helps to see the pressure contours: they have a little kink at the frontal lines. My favorite view at windy.com for that is: color as precipitation, pressure contours, and particle wind animation.
There are some related discussion here https://www.morganscloud.com/2017/06/28/grib-weather-files-you-gotta-see-the-rain/