Decrease line-height (line spacing) for code without highlighting.

Summary

When using pseudographics to create graphs, there are visible gaps between vertical elements.

The UI bug is reproduced in any browser and OS

Steps to reproduce

1. Create code-box with box-drawing characters:

┏━━━━━━━━━━┓
┃ Shard_1  ┃
┗━━━━━┯━━━━┛
      │
┏━━━━━┷━━━━┓
┃ Shard_2  ┃
┗━━━━━━━━━━┛

Example Project

This is independent from projects.

What is the current bug behavior?

Has gaps:

What is the expected correct behavior?

No gaps:

Output of checks

This bug happens everywhere.

Possible fixes

Decrease from 1.6em to 1.3em

.md pre.plaintext {
    line-height: 1.3em;
}