Themes of ChatMLX Have Issue with Input Method

[owenzhao]

Input method with ChatMLX uses the light background color with white font color. That makes it hard to read. Changing the background color in window style can't help as only the background color is changed, the other parts like font color are not changing accordingly.

[johnmai-dev]

Subsequent optimizations will be made to the theme, and opaque dark and light themes will be added.