.center() changes size of flowchart

I have got this flowchart:

mo.mermaid(
"""
flowchart TD
B[B]
B --> CC]
C --> D[D]
D --> E[E]
E --> F[F]
F --> G[G]
G --> H[H]

%% Define a class for rounded rectangles with transparent fill
classDef roundedRect fill:transparent, stroke:#333, stroke-width:3px, rx:10, ry:10;

%% Apply the class to all nodes
class A,B,C,D,E,F,G,H roundedRect;
"""
)

which is slightly larger than the output cell. When I use the .center() method, the chart gets smaller to fit in the cell. Is it a desired behavior, or a bug?