[Website] update homepage mobile styles

[bullet03]

Resolves #22522

• app padding to Apache Beam Features pillars-item class to create space from the borders
• change styles of footer logos so they don't stretch footer and whole page too much

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[alevtinaboiko]

Verified, works as expected. Reviewed and tested by QA

[bullet03]

@pcoet, could you please help with review?

[bullet03]

@pabloem, could you, please, help with merge?

[bullet03]

@aromanenko-dev, could you kindly help with merge? PR was approved.