Increasing the zoom value makes Mermaid diagram sizes yo-yo

[gy-mate]

Describe the bug

When using the zoom option with a slide that has a Mermaid diagram in it, the graph size only follows the gradually increasing zoom value to a certain point. From then on, the diagram size starts to decrease.

Minimal reproduction

Steps to reproduce the behavior:

1. Run:

   git clone https://github.com/gy-mate/talks
   cd talks/2024-12-10_BME_FLOSS_assignment
   git checkout 8a11af1
   slidev

2. Remove this line: https://github.com/gy-mate/talks/blob/8a11af18b216e5fbf66350ca1bf036f36c2c6b81/2024-12-10_BME_FLOSS_assignment/pages/Python.md?plain=1#L6
3. Open http://localhost:3030/7
4. The Mermaid diagram is quite big but it still doesn't fill the screen:
   
5. Change 2.5 to 1 at https://github.com/gy-mate/talks/blob/8a11af18b216e5fbf66350ca1bf036f36c2c6b81/2024-12-10_BME_FLOSS_assignment/pages/Python.md?plain=1#L3
6. The diagram size decreases:
   
7. Change 1 back to 2.5
8. Change 2.5 to 3
9. The diagram size also decreases:
   

Environment

• Slidev version: 0.51.0-beta.4 (global) and 0.50.0 (local)
• Browser: Safari 18.2 and Google Chrome 131.0.6778.205
• OS: macOS 15.2