### 基线对齐

``` html
文字
<u-button>Error</u-button>
<u-button color="error">Error</u-button>
<u-button color="primary" ghost>Primary</u-button>
<u-button icon="refresh" square></u-button>
<u-button color="primary" icon="refresh" square></u-button>
<u-button icon="create">添加</u-button>
<u-button color="primary" icon="create">添加</u-button>
```