autocapitalize attribute works inconsistently on contenteditable

Phenomenon

The autocapitalize attribute, which controls automatic capitalization on mobile keyboards, works inconsistently on contenteditable elements. The behavior may differ from standard input elements.

Reproduction example

1. Create a contenteditable div with autocapitalize="sentences".
2. On an iOS device, focus the contenteditable.
3. Type text and observe capitalization behavior.
4. Compare with a standard input element with the same attribute.

Observed behavior

• In Safari on iOS, autocapitalize may not work as expected on contenteditable.
• Capitalization behavior may differ from standard inputs.
• The attribute may be ignored in some cases.

Expected behavior

• autocapitalize should work identically on contenteditable and standard inputs.
• Capitalization should follow the specified mode (sentences, words, characters, none).
• Behavior should be consistent across browsers and devices.