Update the default theme

### Description

Update the default Flowset app theme. The current theme is too large; you need to reduce the indents, resize buttons, reduce the size of tables, etc., and make the theme more compact to fit more elements on the screen.

<img width="1727" height="933" alt="Image" src="https://github.com/user-attachments/assets/78f56cb3-cb0f-41b2-886b-858f73f3dad8" />