Created attachment 467479 [details] iOS Safari 15 preview of https://codepen.io/tats-u/pen/YzdKKyN Firefox (OK): https://bugzilla.mozilla.org/show_bug.cgi?id=450088 Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1473297 ## What steps will reproduce the problem? (1) See http://wyw.dcweb.cn/ff3_lb.html (referenced from the Firefox issue page) or https://codepen.io/tats-u/pen/YzdKKyN ## What is the expected result? No extra spaces between Chinese / Japanese letters ## What happens instead? Extra spaces are inserted into Chinese or Japanese sentences ## Please provide any additional information below. Attach a screenshot if possible. In Firefox, - Newline between Chinese/Japanese and western/number/Korean => space - Chinese/Japanese include CJK punctuation marks (e.g. 。、．，「」（）) https://codepen.io/tats-u/pen/poQQVyR CSS Text Module Level 4 (exists since Level 3): https://drafts.csswg.org/css-text-4/#line-break-transform See the EXAMPLE 19.