Block Diagram (Mermaid)

block-beta
columns 3
doc>"Document"]:3
space down1<[" "]>(down) space

block:e:3
      l["left"]
      m("A wide one in the middle")
      r["right"]
end
space down2<[" "]>(down) space
db[("DB")]:3
space:3
D space C
db --> D
C --> db
D --> C
style m fill:#d6d,stroke:#333,stroke-width:4px