Fix some layout issues and refactor js code

[issammani]

This PR fixes some layout issues mainly:

• Changes font-size from pt to px as it's not recommended. [ Source ]
• Fixes table and image overflow on smaller screens.
• Removes center block since its obsolete. [ Source ]
• Fixes image aspect ratio problem and resizes big images.

This PR also introduces some JS changes mainly:

• Removes gen_mail_to_link function.
• Moves the addDownloadLink into a new js file.
• Refactors addDownloadLink.

[ghost]

All CLA requirements met.