[Bug] Nav items spacing and alignment

[VedantPatil-99]

Navbar (right-side) layout overflows after scaling the browser width down.
And left-side items are crowding.

Steps to Reproduce

1. Open the ECharts website.
2. Scale the browser width down to roughly 700px-900px.
3. Observe the right alignment of the nav-items (language and GitHub icon) and text-crowding on the left.

Current Behavior

Crowded and overflowing region is shown within red-box

Expected Behavior

Any additional comments?

I have already implemented these changes locally and verified them. I am ready to submit a Pull Request to apply these improvements.