[Bug] Nav items spacing and alignment

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.

Start by locating the ECharts website navbar components and their responsive styles, then reproduce the issue at roughly 700px–900px wide. Done means the right-side language and GitHub items remain aligned without overflow and the left-side items no longer crowd, while the expected layout is preserved at wider widths.

Written by the indexing model from the issue text.