Cellfire preview

As an example:
```css
.document-style table td { padding: 0px;  }
.document-style .data { background-color: @preview-bg; padding: 0px; vertical-align:top; padding-left:10px; }
```
to
```css
.document-style {
  table td {
    padding: 0px;
  }
  .data { background-color: @preview-bg; padding: 0px; vertical-align:top; padding-left:10px; }
}
```