paper-toggle-button cannot be centered

[marto55555]

paper-toggle-button can no longer be centered in the middle of the page. In the past, I used this code, but it no longer works:
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[bicknellr]

repro here. Looks like we need display: inline-flex;.

[bicknellr]

.. or the display: inline-block; in :host needs to be moved after the mixins overriding it, but I'm not sure what the flex is being used for - it might be needed.

[tonlie]

the reason seems to be the absolute left/right margin for the toggle-container implemented in 182ecb2. Setting it to auto (as in margin: 4px auto;) will center it properly.

I'm not sure, why the left/right margin has to be set to 1px, maybe @notwaldorf can help?

Also, if your paper-toggle-button does not need a label, make sure to set the distance between the button and the label to 0px by applying the the --paper-toggle-button-label-spacing mixin, otherwise the button will be slightly offset to the left!