Code block file names clash with invalid language specifiers

[jonasreiher]

Description

When using a valid language specifier in a code block, file names are displayed correctly. With invalid language specifiers, they overlap with the code content.

Steps To Reproduce

1. Put this code block in your markdown, with an invalid language specifier xyz:

```xyz {filename="test.md"}
Hello
```

2. It renders like this:
   

3. Use a valid language specifier instead, e.g. txt:

```txt {filename="test.md"}
Hello
```

4. It renders correctly like this:
   

Expected Behavior

Render the filename correctly above the code even if the language specifier is mistyped. The wrong language specifier should only affect syntax highlighting.

Environment

• Hugo Version: v0.122.0-extended
• Browser/OS: Safari + Firefox, MacOS
• Theme Version: v0.7.1

[imfing]

Thank you! Looks like a CSS issue, will look into it.