config: noClasses option issue

[foxisawesome]

I have checked all the prerequisites below and I'm yet experiencing a problem

• Read the README.md
• Have the extended version of Hugo installed
• Used the exampleSite's config.toml as a reference

Describe the bug
While changing noClasses=true in config.toml file. the site cannot be change to light mode. It stuck at dark mode.

Desktop (please complete the following information):

• chrome 88

[onweru]

Umh, is this the line you're trying to edit?

[foxisawesome]

Actually, I am trying to change line 39: noClasses = true in the file: exampleSite\config.toml. everything else untouched. Then I compiled the site. Went to chrome, found the the dark mode switch would NOT work for pages having python code highlighting blocks. Pages not having hightlight blocks can switch between dark mode and light mode.

[onweru]

Oh, I see ... changing that will indeed break the theme. I will see if that's something I can accommodate going forward.

[hupfdule]

The same is true for code blocks with an invalid language specified.

For example the following code block breaks the dark mode (for that page):

```invalid
some test
```

If the term invalid is removed the dark mode works again.

[onweru]

The same is true for code blocks with an invalid language specified.

For example the following code block breaks the dark mode (for that page):

```invalid
some test

If the term `invalid` is removed the dark mode works again.

@hupfdule, I couldn't reproduce the darkmode breaking when I copied this