[Bug]: Features page hero and sections have uneven spacing and card styling

### Consisely describe the issue

- On feature page, the hero section, `PageHeader` have uneven alignment and spacing.
- The seal image on mobile device looks not in place and should only be present on the desktop devices.
- "Getting to know Podman" section cards doesn't have any background and is not distinct at all.

### Upload screenshots or screen recordings

### LLM Policy

- [x] This issue is human-written, and folow up comments will also be human-written

Start at the features page and its PageHeader component, then compare the supplied desktop and mobile screenshots with the current layout. Check the responsive hero, seal image visibility, and “Getting to know Podman” cards; done means consistent spacing and alignment, the seal appears only on desktop, and the cards are visually distinct.

Written by the indexing model from the issue text.