Summary
In ChatGPT’s input textarea, full-width Japanese brackets “」「” overlap (render with near-zero width) on Blink-based browsers (Chrome, Edge, Brave), but display normally on Firefox (Gecko-based). Other applications and websites (e.g., VS Code, Twitter, Google search bar) show correct rendering with the same fonts, indicating a Blink-specific rendering behavior involving CSS OpenType features.
Steps to Reproduce
- Open https://chat.openai.com (any model, any theme) in a Blink-based browser (Chrome, Edge, Brave).
- Switch keyboard to a Japanese IME.
- Type “」「” (full-width Japanese brackets).
- Observe brackets overlapping horizontally and becoming unreadable.
Expected
Brackets render with proper spacing.
Actual
Brackets overlap significantly in Blink-based browsers (see screenshots).
Firefox (Gecko-based) does not exhibit this issue.
Environment
- Windows 11 JP 23H2
- Browsers tested:
Issue reproduced: Chrome 124, Brave 1.57.101, Edge 124 (Blink-based)
Issue not reproduced: Firefox 125 (Gecko-based)
- No browser extensions, Shields/tracking protection disabled, tested in private/incognito mode
- Fonts tested: Noto Sans JP, Noto Sans Mono CJK JP, BIZ UD Gothic, BIZ UD Mincho
Technical Investigation
ChatGPT’s textarea applies this CSS via Tailwind CSS:
font-feature-settings: "palt";
Computed styles typically interpret this as "palt" 1, explicitly enabling the OpenType “proportional alternates (palt)” feature, which reduces punctuation widths (including Japanese brackets). Blink browsers apply this feature in a way that drastically reduces glyph widths, causing bracket glyphs to overlap horizontally.
Gecko (Firefox) implements this feature differently, preventing glyph overlap.
Explicitly disabling “palt” resolves this issue in Blink browsers immediately:
textarea { font-feature-settings: "palt" 0 !important; }
Temporary Workaround
Inject the above CSS rule using Stylus/Tampermonkey extensions or browser DevTools until an official fix is released.
Impact
This issue significantly impairs readability and usability for Japanese and other CJK-language users on Blink-based browsers, negatively impacting professional use of ChatGPT in affected locales.
Suggested Fix:
Explicitly disable the font-feature-settings: "palt" feature on the ChatGPT textarea to ensure consistent and correct rendering across all major browsers.
