Tested on IE11 and Edge: the style is only applied to the quotation mark, not the letter following it.

Tested the issue Windows, Mac & Linux using Chrome Beta# 53.0.2785.70 and is able to reproduce the issue.
This is a Regression Issue in M46 builds. Bisect tool did not provide the exact CL details, so providing the change log manually.
Chrome Good Build :: 46.0.2474.0
Chrome Bad  Build :: 46.0.2475.0

CHANGE LOG --
https://chromium.googlesource.com/chromium/src/+log/46.0.2474.0..46.0.2475.0?pretty=fuller&n=10000

From the CL, assigning the issue to concern owner. Pardon me if it has nothing to do with your changes and if possible please assign it to conern owner.
Thank You.

Why did you assign this to me? My only changes in that huge range is some unit test and documentation.

I suggest that you investigate the 8 blink rolls (those commits with third_party/WebKit in the message).
Here are all rolls: https://chromium.googlesource.com/chromium/blink/+log/5c812a3..78cb832

Apologies.
Changing the status to Untriaged so that the issue would get addressed.
Thank You.

All browsers renders this differently and it is unclear what the "correct" behavior is.

The spec indicates that punctuation should be included and that works across browsers:

Punctuation (i.e, characters defined in Unicode in the "open" (Ps), "close" (Pe), "initial" (Pi). "final" (Pf) and "other" (Po) punctuation classes), that precedes or follows the first letter should be included. [UNICODE]
https://drafts.csswg.org/selectors-3/#first-letter

Spaces are *not* included in that list though and Safari appears to be the only browser that includes both in first-letter.

Regarding comment #6: the spec also notes that "In some cases the ::first-letter pseudo-element should include more than just the first non-punctuation character on a line." I would agree that this is one of those cases.

The rule about punctuation makes a lot of sense for opening quotation mark (such as in the example in the spec), and the opening quotation mark in French cannot go without a space (https://en.wikipedia.org/wiki/Quotation_mark#French).

Also, if the element starts with non-breaking spaces and then a letter (without having a punctuation in front), the style gets applied to the spaces as well (see leading-space.html attachment), so the spaces are already included in the pseudo-element sometimes.

At least, the other part of the bug (the style being applied to the first letter of the first sub-element) should be fixed. It doesn't make sense to apply the :first-letter style to text that can be far away from the beginning of the element.

Deleted: leading-space.html 201 bytes

leading-space.html 201 bytes View Download

We should try to get the spec amended to clarify the expectations here so that all browsers can render it the same way.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

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