Safari 17.4 introduces vertical writing mode support for form control elements on macOS, iOS, iPadOS, and visionOS, catering to East Asian languages like Chinese, Japanese, and Korean. The industry has committed to enhancing cross-browser support for vertical text, which can be achieved by using the CSS writing-mode property. WebKit underwent extensive changes to accommodate vertical writing modes for form controls, ensuring controls like checkboxes and radio buttons appear consistent in all writing modes. Safari 17.4 also includes support for new controls like . The update aims to improve internationalization support and empower authors to create diverse content. Feedback on this feature is encouraged via social media or WebKit bug reports.
https://webkit.org/blog/15190/implementing-vertical-form-controls/