Error on d-button-group.

[maxchou415]

Current Behavior

When I use <d-button-group> in Nuxt, It will be shows these error:

[Vue warn]: Error in beforeCreate hook: "ReferenceError: document is not defined"

found in

---> <DButtonGroup> at /Users/hisk/Projects/GitHub/shards-vue/src/components/button-group/ButtonGroup.vue

and my code was:

<d-button-group>
        <d-button>Left</d-button>
        <d-button>Middle</d-button>
        <d-button>Right</d-button>
</d-button-group>

Steps to Reproduce

1. Just use <d-button-group> this component, and with SSR mode in Nuxt.js.

Thanks.