doc: fix dark theme on empty location hash

[felixmariotto]

When accessing https://threejs.org/docs/ with a browser with dark theme preference, this is what shows up :

Tested on Chrome and Opera.

It seems that the iframe with an empty src has an opaque white background overlapping the body background.

Original dark mode support PR by @mrdoob for reference : #17729

After the commit :

[Mugen87]

I guess a similar fix makes also sense for examples. Without calling it without an example, dark mode looks like so:

[felixmariotto]

I guess a similar fix makes also sense for examples.

It looks like this PR fixes https://threejs.org/examples/ as well.

[Mugen87]

It's a change in docs/index.html. How does this affect the examples page?

[felixmariotto]

Indeed you are right... It's weird I can't reproduce the wrong dark theme at https://threejs.org/examples/ locally

I will investigate and make a new PR

[Mugen87]

It's weird I can't reproduce the wrong dark theme at https://threejs.org/examples/ locally

True. I wonder what makes the difference...

[mrdoob]

TIL about unset 😮

[mrdoob]

It's weird I can't reproduce the wrong dark theme at https://threejs.org/examples/ locally

True. I wonder what makes the difference...

I went down this rabbit hole before.
I concluded it was a bug in Chrome but was not able to spend enough time to figure out the details...

[mrdoob]

Thanks!