Milo's house is the sleek modern number in the background back there, and the yard's only like that sometimes. The mess is inside most of the time, really. It's lived in, a little run down, but it's actually quite cozy inside with slanted ceilings and some high windows. There's a small second story, but the second story only contains his bedroom (with a slanted ceiling that goes almost to the floor on one side) and a bathroom.
So this is Milo's bedroom. He's got money, yeah, and he's got some decorative sense, but he's also a messy housekeeper so this is what it would look like it was clean.
There are books everywhere, shelves overstuffed and then stacks leaning against door frames and piled on the stairs. And just... stuff. all over. and then little mini fairy-houses on shelves and in teacups where he can shrink down and hang out.