基本用法
`<button>默认按钮<button>`
不同颜色按钮
~~~
<button light>Light</button>
<button>Primary</button>
<button secondary>Secondary</button>
<button danger>Danger</button>
<button dark>Dark</button>
~~~
不同颜色描边按钮
~~~
<button light outline>Light Outline</button>
<button outline>Primary Outline</button>
<button secondary outline>Secondary Outline</button>
<button danger outline>Danger Outline</button>
<button dark outline>Dark Outline</button>
~~~