That's just literally transcribing English to Japanese using katakana, to be fair. Actual Japanese for text color would be "文書の色" (bunsho no iro) and font size

That's just literally transcribing English to Japanese using katakana, to be fair. Actual Japanese for text color would be "文書の色" (bunsho no iro) and font size would be "文字の大きさ" (moji no ookisa), and variants thereof. So a Japanese dev who doesn't speak English would think: "文字の大きさを設定するために「text-color」と入力する。" and it would, again, make logical sense from both human and computer perspectives.