Benchmark styles broken for narrow and mid-range screen widths

[chalin]

• [ ] Fix styles for mobile displays
• [ ] Fix styles for mid-range screens
• [ ] Benchmark styles file should not unconditionally style main elements, as main is used by Docsy.

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Mobile

Example illustrating the formatting problems:

Mid-range screens

This is probably just a question of a misaligned media breakpoint.

Here's an example from https://opentelemetry.io/docs/collector/benchmarks/ that shows the misformatting on mid-range screens: