Update to Leo's product header

[aguscruiz]

Description

Changes:

• Font size changes to 19px with 19px line-height (uses a Nala style that needs to be uploaded called Sidebar product title)
• The header should have a 60px minimum height. But give the top-bottom paddings a 16px value in case it needs to grow a bit more.
• Product title is always lowercase
• Product name changes to "leo ai"
• Added a "close" icon on the right to close the panel (Desktop and Android)

Design
https://www.figma.com/file/MNwi0uwXNhkAbPiJ86G4vm/%E2%9C%A8-Leo?type=design&node-id=1506%3A7892&mode=design&t=i7noPdyJ4idIyTyS-1