Issue description

when I add code block like this:

```c
getopt(argc, argv, "a:b:");
```

the ":b:" will be rendered as a big red "B"

Theme version

current stable

Hugo version

hugo v0.148.1-98ba786f2f5dca0866f47ab79f394370bcb77d2f+extended linux/amd64

Which browser rendering engines are you seeing the problem on?

Chromium (Google Chrome, Microsoft Edge, Brave, Vivaldi, Opera, etc.)

URL to sample repository or website

No response

Hugo output or build error messages