Fix zindex in safari

[micalgenus]

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[coveralls]

Coverage remained the same at 94.99% when pulling 6732eb7 on micalgenus:master into 1991ed2 on fkhadra:master.

[fkhadra]

Hello @micalgenus,

Sorry for the late reply. Could you share with me a codesandbox that reproduce the issue please.

Thank you

[micalgenus]

before: https://codesandbox.io/embed/xenodochial-kirch-t3ch0

after: https://codesandbox.io/embed/naughty-bose-ljo4f

[fkhadra]

@micalgenus thank you for sharing !