when importing d2-file that define 'style' and 'classes', absolute path is better than relative path.

move "cccc.d2" "./bar/cccc.d2"

├─d2
│ │ bokura-config.d2
│ │
│ └─foo
│　　│ aaaaa.d2 (classes{ ...@../bokura-config.classes })
│　　│ bbbbb.d2 (classes{ ...@../bokura-config.classes })
│　　│ (ccccc.d2) <-OK
│　　│
│　　└─bar
│　　　ccccc.d2 (classes{ ...@../bokura-config.classes }) <- NG (../../ <-OK)