Backspace removes a whole composed syllable instead of a single jamo

Phenomenon

When editing Korean text in a contenteditable element, pressing Backspace removes the entire composed syllable instead of a single jamo. This makes fine-grained correction difficult and differs from native input fields on the same platform.

Reproduction example

1. Focus the editable area.
2. Activate a Korean IME.
3. Type one composed syllable (for example, three jamo characters that form a syllable).
4. Press Backspace once.

Observed behavior

• The entire syllable is removed by a single Backspace press.
• The event log shows only one beforeinput / input pair for the deletion.

Expected behavior

• Each Backspace press removes a single jamo, matching how native inputs behave in the same OS, browser, and IME configuration.

Notes

• Compare behavior with a plain <input> element in the same environment to confirm the difference.
• This behavior can affect cursor movement, undo granularity, and diff calculation for text editors built on top of contenteditable.