Edit default font size of sozi-frame-number (too small) #748

Hello author!
Sozi is an extremely powerful slideshow editing tool that has helped me a great deal in both daily life and work. However, one issue has been bothering me for a long time: the default font size of sozi-frame-number in Sozi slides is too small.
Every time I finish editing slides, I have to open the sozi.html file manually to adjust this value. It becomes extremely inconvenient when I have multiple slides or edit files frequently.
Could you please add an option in the Sozi UI to customize the font size of frame numbers directly?
Thank you so much for your amazing work!