[Bug] Affix (side panel) is shown for small viewports on iPad

[iadonkey]

Describe the bug
The "affix" (side panel) is shown on an iPad even if the viewport size is small when using a split view

To Reproduce

1. On an iPad create a split view
2. In the smaller view, go to docfx
3. The affix is visible

Expected behavior
The affix should not be shown for such a small viewport

Context (please complete the following information):

• OS: Windows
• Docfx version: 2.72.1

Additional context
This only happens with the modern theme I think with default it looks ok