fix: Diagram is too wide for 148mm page width

[ktgw0316]

P. 426 of ctfp--98b71ac.pdf:

[drupol]

Just for my own information, why is this an issue ?

[ktgw0316]

For printed books, it's generally considered standard practice to ensure content doesn't extend beyond the page margins, but for digital editions, that might be worrying too much.