Test homepage changes for preview.

[craigbox]

Working PR; do not merge.

[craigbox]

https://deploy-preview-14996--preliminary-istio.netlify.app/

Before this is "finished" we should:

• use proper CSS for the subheading
• use proper CSS to get the "What is Istio" text the right size
• add some sort of graphic to float right in that section (mockup)
• fix the alignment of the logos (vertically center the images)
• fix the width of the logos (test on mobile)
• choose different logos; those were just the first that we had full case studies for
• align the bottom of the buttons in the "features" section

(@mikemorris @keithmattix or any other volunteers!)

[mikemorris]

Suggested fixes in craigbox#3 for

• align the bottom of the buttons in the "features" section

and in craigbox#4 for

• use proper CSS for the subheading
• use proper CSS to get the "What is Istio" text the right size

Docs for case study scroller that needs fixing are at https://splidejs.com/guides/auto-width/ if anyone wants to give that a shot, I found it a bit glitchy and ran out of time.

[craigbox]

I've merged in Mike's fixes (thanks!) and think that we could probably go live with this, but we would like to still make the following improvements:

• change the "What is Istio" section into body text & a floating image (see mockup)) - depends on actually having an image
• make the slider work on mobile. I didn't have any luck with the autoWidth setting myself and figuring out why is beyond my interest and ability.

[istio-testing]

@craigbox: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
lint_istio.io	55c542a	link	true	/test lint

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