Thank you Guarav,
For the Invert Colors mode, this is a known issue and we may add a different color scheme in the future. However, if you use the Smart Invert setting of iOS, things should look as expected. Please let us know if Smart Invert does not work for you for any reason.
We will soon add a setting to always show all buttons on the keyboard.
For the half-screen mode, this is something we're working on.