Custom app theme colors – include text inputs?

Let's say I have a messaging app, where multiple users can post messages to a common discussion board. Each message on the board contains the user's name and the user's comment. The color for the comment can be "themed" by the app's admin.

Should I set the color of the text input for the comment to match how it is displayed on the discussion board, or should I leave it as the default color - as set by the platform the app is running on?

I feel like users don't expect to see a "color" in text inputs, but I also think that typing in a comment in 1 color, and then immediately seeing it in another feels slightly broken.

A or B?