[Feature] redesign landing page in new style of website

[lixuna]

Is your feature request related to a problem? Please describe.

• cncf.io was redesigned before KubeCon EU 2022
• some pages have been redesigned in the new style, but others like the K8s Conformance and CNF Certification are still in the old style

Describe the solution you'd like

• Collaborate on a redesigned version of cncf.io/cnf

Related issues:

• 14

• 15

• 16