Consider matching DOM order for Sky Nav elements when JS is disabled for better accessibility

When JS is disabled:
- the "Menu" button is hidden
- the Sky Nav is open

## Current implementation

The DOM order of the nav does not match the visual order in the current solution:
Current tab order count | Current tab order in action
--- | ---
| 

## Proposed solution

We should consider allowing the visual order to match the DOM order when JS is disabled. We might even consider centering the Cloud Four logo since the button is not shown:
Proposes tab order count | Proposed tab order in action
--- | ---
| 

## Other considerations

- The gradient no longer matches the original design in the proposed solution

## Related

- https://web.dev/visual-order-follows-dom/

首先定位 Sky Nav 的实现，并在禁用 JavaScript 的情况下检查其 DOM 和视觉顺序。将键盘 Tab 顺序与提议的屏幕截图进行比较，然后确认导航顺序在考虑 logo 位置和渐变设计问题的同时保持一致。

由索引模型根据 Issue 内容生成。