Improve style of the game mode

[PabloGOP]

Needs to be addressed:

• [x] Global layout and responsiveness
• [x] Progress bar is not centered and has to be more beutiful
• [x] Total time timer has no style and seems out of place as we ve already implemented question based time
• [x] Question and responses fonts
• [x] Colors used to mark right/wrong questions have been put as 'red' and 'green' instead of using the theme
• [x] Pause button