Old CSS syntax with prefixes - otsukare

Working on Web Compatibility issues for Japan is a kind of nightmare. The two biggest offenders are first versions of WebKit flexbox and gradient. Basically Web developers hurried to use flexbox for their Web sites, but never dared fixing it when the new stable syntax had been released. Web Developers used CSS prefixes to support browsers Browsers have to support Web sites because of their outdate

[Rockridge]

日本のWebサイトの互換性を損なう要因として、WebKitに導入されたCSS flexboxとCSS gradientの初期の仕様を採用しつつ、最新仕様に更新しないままになっていることが挙げられるという。