fix(directives): set copy directive z-index below nav

[Kevin-K]

Fixes: #768

Sets the z:index on the copy-button directive to 4 to be lower than the main navbar.

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[Kevin-K]

I signed it!

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[christianliebel]

This is not enough. Actually, there’s no reason for the z-index to be larger than 1, so you should set it to this exact value.

[christianliebel]

@Kevin-K Unfortunately, setting the z-index to 4 is not enough, because you miss the nav bar in smartphone mode:

There doesn’t seem to be any reason why z-index should be larger than 1. Therefore I suggest that you update your PR and set z-index: 1. This fixes copy-button.

[Kevin-K]

Good catch, I didn't consider the side-nav z-indexes.

Moved it to z-index: 1. While reading the tutorials I didn't notice anywhere where the copy button sits over any layered content. If it does and I missed it, setting up to z-index: 3 will remain under the side-nav when pushed to the xs layout.