UI improvements for the product page

[g123k]

Hi everyone,

After #5749, it seems some changes and the existing UI need some tweaks:

• The space between sections is never the same
• There is a huge space after the price section… for nothing
• On Android, the action bar needs an extra padding due to the conflicting navigation bar
• On Android, the buttons in the action bar are not centered (??)

[teolemon]

We can also harmonize the website and price cards

)