In the UK we mostly speak English as the first language. But software such as WordPress is written in American English, not British English.
For an internationalised application the output of text strings may be translated and therefore the localised version behaves slightly differently.
How would you translate
check color to British English? Probably to
check colour but
cheque colour may be valid in a banking application.
It’s a lot more obvious with foreign languages when there are words and / or character sets you don’t understand.
<script> tag into a CSS file?