Online editor enhancement: close file UX

As a user I want to easily find the close button so that I can dismiss the editor.

As a user, when closing the file or clicking the logo to go back to the landing page:

• I want to be informed that my progress will be not be saved so I am aware that work could be lost if not saved.
• I need the option to save the file so I will not risk losing important work.

Notes:
1-) Making the close icon larger;
2-) Make the box around the title show up during the roll-over as well (currently just the cursor changes to the text editor)

Verification conditions:

• Mockups of revised close button and interaction.
• Design reviewed.