In the "hosts" tab; is the a CSS file or something that lets me change the grey dot (for offline hosts) to something else? Green and grey look very similar (to me). (As an aside, maybe change the dot size and the colour of the dot depending on how long the host has been offline, as a sort of "health" indicator?)

This is great feedback! Any other accessibility suggestions we should take a look at?

This is a minor thing really, but there are no tool tips for the (!) (circle with bang) or "Used by" columns; I can never remember what these are for (they are always empty or contain three greyed out dashes).