Thread:Talk:Requests for comment/ResourceLoader CSS Extensions/Points from Bergi/reply

@-mw-extendedcss is ONLY for things that don't fit in with standard css. Things like -mw-file will work unconditionally because they don't conflict. However things like converting border-radius: ...; to {-moz-,-webkit-,}border-radius: ...; have a slight risk of conflicting with existing css that already specifies all the vendor prefixes. In those cases we don't want extended css on because we could go and break a previously working stylesheet.

I don't like the idea of -mw-embed-url and -mw-embed-file. That's essentially defining a -mw-embed-* pattern that requires us to create a new function for each and every non-embed function we add. I picked -mw-embed( ... ); because it will work with everything. Native url; We add in -mw-file, that'll work. Throw in a -mw-thumb, that'll work too. Say in the future we create a icon framework extension that lets action tabs have icons defined by the wiki and lets skins include the icons using -mw-icon( 'watch', 16 ); then we'd have to go back and also implement -mw-embed-icon.

calc is defined by css3-values, I'm not making up syntax here. The idea is to allow the portion of static calculations we can pre-process to be used. ie: We'll substitute calc( 500px + 15px ); but not calc( 100% + 5em ); because it's not possible to preprocess two different units together. yes my example could use a variable system, however that does not exclude calc. Because if you do add a variable system you will absolutely need calc at that point. Because authors are inevitably going to need something like "$theboxwidth - 1px". Nearly every case where you would want to repeat numbers several times will be in a case where the numbers are not all the same.