MediaWiki has some "content" styles that only apply inside .mw-body. However, skins often have layout styles on .mw-body (e.g. Vector), making it impossible to just add class="mw-body" anywhere (e.g. Vector adds margin-left and a blue border).
These need to be changed to either apply everywhere, if that's okay (essentially, replacing .mw-body foo with just foo), or changed to apply to a more narrow selector that can be added in random places (e.g. .mw-body-content).
Vector's styles for external links, headings, table of contents, etc. suffer from the same problem.
What this means in practice: if you want to have a heading styled like normal headings in Vector, or an external link styled with the usual icons, and your content is not inside <div class="mw-body"> (e.g. it's inside a OOjs UI dialog), you can't.
Previous attempts at resolving this (abandoned): https://gerrit.wikimedia.org/r/#/c/158803/ https://gerrit.wikimedia.org/r/#/c/158854/
resources/src/mediawiki.legacy/commonPrint.css:
106: .mw-body {
119: #column-content .mw-body {
172: .mw-body a.external.text:after,
173: .mw-body a.external.autonumber:after {
180: .mw-body a.external.text[href^='//']:after,
181: .mw-body a.external.autonumber[href^='//']:after {
resources/src/mediawiki.legacy/oldshared.css:
466: html > body.rtl .mw-body ul#filetoc {
resources/src/mediawiki.skinning/content.externallinks.css:
12: .mw-body a.external,
22: .mw-body a.external[href^="mailto:"],
30: .mw-body a.external[href^="ftp://"],
38: .mw-body a.external[href^="irc://"],
39: .mw-body a.external[href^="ircs://"],
47: .mw-body a.external[href$=".ogg"], .mw-body a.external[href$=".OGG"],
48: .mw-body a.external[href$=".mid"], .mw-body a.external[href$=".MID"],
49: .mw-body a.external[href$=".midi"], .mw-body a.external[href$=".MIDI"],
50: .mw-body a.external[href$=".mp3"], .mw-body a.external[href$=".MP3"],
51: .mw-body a.external[href$=".wav"], .mw-body a.external[href$=".WAV"],
52: .mw-body a.external[href$=".wma"], .mw-body a.external[href$=".WMA"],
60: .mw-body a.external[href$=".ogm"], .mw-body a.external[href$=".OGM"],
61: .mw-body a.external[href$=".avi"], .mw-body a.external[href$=".AVI"],
62: .mw-body a.external[href$=".mpeg"], .mw-body a.external[href$=".MPEG"],
63: .mw-body a.external[href$=".mpg"], .mw-body a.external[href$=".MPG"],
71: .mw-body a.external[href$=".pdf"], .mw-body a.external[href$=".PDF"],
72: .mw-body a.external[href*=".pdf#"], .mw-body a.external[href*=".PDF#"],
73: .mw-body a.external[href*=".pdf?"], .mw-body a.external[href*=".PDF?"],
82: .mw-body a.extiw,
83: .mw-body a.extiw:active {
88: .mw-body a.external {
resources/src/mediawiki.skinning/elements.css:
53: .mw-body a.extiw,
54: .mw-body a.extiw:active {
58: .mw-body a.extiw:visited {
62: .mw-body a.extiw:active {
67: .mw-body a.external {
71: .mw-body a.external:visited {
75: .mw-body a.external:active {
79: .mw-body a.external.free {
resources/src/mediawiki.special/mediawiki.special.search.styles.css:
20: /* needs extra specificity to override `.mw-body p` selector */
21: .mw-body .mw-search-nonefound {screen-hd.less:
5: .mw-body {
components/common.less:
30: .mw-body {
components/externalLinks.less:
3: .mw-body {