Rewrite the user-agent stysheet(s)

Based on https://html.spec.whatwg.org/multipage/rendering.html
rather than http://dev.w3.org/csswg/css2/grammar.html

6 files changed, 795 insertions, 130 deletions

diff --git a/resources/iso-8859-8.css b/resources/iso-8859-8.css
new file mode 100644
index 00000000000..fd97ef5807f
--- /dev/null
+++ b/resources/iso-8859-8.css
@@ -0,0 +1,23 @@
+/*
+
+https://html.spec.whatwg.org/multipage/rendering.html#bidi-rendering
+
+> When the document's character encoding is ISO-8859-8,
+> the following rules are additionally expected to apply, following [user-agent.css]
+
+*/
+
+@namespace url(http://www.w3.org/1999/xhtml);
+
+
+address, blockquote, center, div, figure, figcaption, footer, form, header, hr,
+legend, listing, main, p, plaintext, pre, summary, xmp, article, aside, h1, h2,
+h3, h4, h5, h6, hgroup, nav, section, table, caption, colgroup, col, thead,
+tbody, tfoot, tr, td, th, dir, dd, dl, dt, menu, ol, ul, li, [dir=ltr i],
+[dir=rtl i], [dir=auto i], *|* {
+  unicode-bidi: bidi-override;
+}
+input:not([type=submit i]):not([type=reset i]):not([type=button i]),
+textarea, keygen {
+  unicode-bidi: normal;
+}
diff --git a/resources/presentational-hints.css b/resources/presentational-hints.css
new file mode 100644
index 00000000000..dcccbf9a64b
--- /dev/null
+++ b/resources/presentational-hints.css
@@ -0,0 +1,261 @@
+/*
+https://html.spec.whatwg.org/multipage/rendering.html#presentational-hints
+*/
+
+@namespace url(http://www.w3.org/1999/xhtml);
+
+
+pre[wrap] { white-space: pre-wrap; }
+
+/*
+FIXME: also "align descendants"
+https://html.spec.whatwg.org/multipage/rendering.html#align-descendants
+*/
+center, div[align=center i], div[align=middle i] { text-align: center; }
+div[align=left i] { text-align: left; }
+div[align=right i] { text-align: right; }
+div[align=justify i] { text-align: justify; }
+
+
+br[clear=left i] { clear: left; }
+br[clear=right i] { clear: right; }
+br[clear=all i], br[clear=both i] { clear: both; }
+
+
+ol[type=1], li[type=1] { list-style-type: decimal; }
+ol[type=a], li[type=a] { list-style-type: lower-alpha; }
+ol[type=A], li[type=A] { list-style-type: upper-alpha; }
+ol[type=i], li[type=i] { list-style-type: lower-roman; }
+ol[type=I], li[type=I] { list-style-type: upper-roman; }
+ul[type=none i], li[type=none i] { list-style-type: none; }
+ul[type=disc i], li[type=disc i] { list-style-type: disc; }
+ul[type=circle i], li[type=circle i] { list-style-type: circle; }
+ul[type=square i], li[type=square i] { list-style-type: square; }
+
+
+table[align=left i] { float: left; }
+table[align=right i] { float: right; }
+table[align=center i] { margin-left: auto; margin-right: auto; }
+:matches(thead, tbody, tfoot, tr, td, th)[align=absmiddle i] {
+  text-align: center;
+}
+
+caption[align=bottom i] { caption-side: bottom; }
+:matches(p, h1, h2, h3, h4, h5, h6)[align=left i] { text-align: left; }
+:matches(p, h1, h2, h3, h4, h5, h6)[align=right i] { text-align: right; }
+:matches(p, h1, h2, h3, h4, h5, h6)[align=center i] { text-align: center; }
+:matches(p, h1, h2, h3, h4, h5, h6)[align=justify i] { text-align: justify; }
+:matches(thead, tbody, tfoot, tr, td, th)[valign=top i] { vertical-align: top; }
+:matches(thead, tbody, tfoot, tr, td, th)[valign=middle i] { vertical-align: middle; }
+:matches(thead, tbody, tfoot, tr, td, th)[valign=bottom i] { vertical-align: bottom; }
+:matches(thead, tbody, tfoot, tr, td, th)[valign=baseline i] { vertical-align: baseline; }
+
+td[nowrap], th[nowrap] { white-space: nowrap; }
+
+table:matches([rules=none i], [rules=groups i], [rules=rows i], [rules=cols i], [rules=all i]) {
+  border-style: hidden;
+  border-collapse: collapse;
+}
+
+table[border] {
+  border-style: outset;
+  /*
+  FIXME: only if border is not equivalent to zero
+  https://html.spec.whatwg.org/multipage/rendering.html#magic-border-selector
+  */
+}
+table[frame=void i] { border-style: hidden; }
+table[frame=above i] { border-style: outset hidden hidden hidden; }
+table[frame=below i] { border-style: hidden hidden outset hidden; }
+table[frame=hsides i] { border-style: outset hidden outset hidden; }
+table[frame=lhs i] { border-style: hidden hidden hidden outset; }
+table[frame=rhs i] { border-style: hidden outset hidden hidden; }
+table[frame=vsides i] { border-style: hidden outset; }
+table[frame=box i], table[frame=border i] { border-style: outset; }
+
+
+table[border] > tr > :matches(td, th),
+table[border] > :matches(thead, tbody, tfoot) > tr > :matches(td, th) {
+  /*
+  FIXME: only if border is not equivalent to zero
+  https://html.spec.whatwg.org/multipage/rendering.html#magic-border-selector
+  */
+  border-width: 1px;
+  border-style: inset;
+}
+
+table:matches([rules=none i], [rules=groups i], [rules=rows i]) > tr > :matches(td, th),
+table:matches([rules=none i], [rules=groups i], [rules=rows i]) > :matches(thead, tbody, tfoot) > tr > :matches(td, th) {
+  border-width: 1px;
+  border-style: none;
+}
+table[rules=cols i] > tr > :matches(td, th),
+table[rules=cols i] > :matches(thead, tbody, tfoot) > tr > :matches(td, th) {
+  border-width: 1px;
+  border-style: none solid;
+}
+table[rules=all i] > tr > :matches(td, th),
+table[rules=all i] > :matches(thead, tbody, tfoot) > tr > :matches(td, th) {
+  border-width: 1px;
+  border-style: solid;
+}
+
+table[rules=groups i] > colgroup {
+  border-left-width: 1px;
+  border-left-style: solid;
+  border-right-width: 1px;
+  border-right-style: solid;
+}
+table[rules=groups i] > :matches(thead, tbody, tfoot) {
+  border-top-width: 1px;
+  border-top-style: solid;
+  border-bottom-width: 1px;
+  border-bottom-style: solid;
+}
+table[rules=rows i] > tr,
+table[rules=rows i] > :matches(thead, tbody, tfoot) > tr {
+  border-top-width: 1px;
+  border-top-style: solid;
+  border-bottom-width: 1px;
+  border-bottom-style: solid;
+}
+
+
+hr[align=left] { margin-left: 0; margin-right: auto; }
+hr[align=right] { margin-left: auto; margin-right: 0; }
+hr[align=center] { margin-left: auto; margin-right: auto; }
+hr[color], hr[noshade] { border-style: solid; }
+
+
+
+iframe[frameborder=0], iframe[frameborder=no i] { border: none; }
+
+:matches(applet, embed, iframe, img, input[type=image i], object)[align=left i] {
+  float: left;
+}
+:matches(applet, embed, iframe, img, input[type=image i], object)[align=right i] {
+  float: right;
+}
+:matches(applet, embed, iframe, img, input[type=image i], object)[align=top i] {
+  vertical-align: top;
+}
+:matches(applet, embed, iframe, img, input[type=image i], object)[align=baseline i] {
+  vertical-align: baseline;
+}
+:matches(applet, embed, iframe, img, input[type=image i], object)[align=texttop i] {
+  vertical-align: text-top;
+}
+:matches(applet, embed, iframe, img, input[type=image i], object):matches([align=absmiddle i], [align=abscenter i]) {
+  vertical-align: middle;
+}
+:matches(applet, embed, iframe, img, input[type=image i], object)[align=bottom i] {
+  vertical-align: bottom;
+}
+/*
+FIXME:
+:matches(applet, embed, iframe, img, input[type=image i], object):matches([align=center i], [align=middle i]) {
+  vertical-align: "aligns the vertical middle of the element with the parent element's baseline."
+}
+*/
+
+/*
+
+Presentational attributes which can not currently be expressed in CSS.
+FIXME: Deal with them with attr(foo dimension) and the like?
+
+body
+  marginheight
+  marginwidth
+  topmargin
+  rightmargin
+  bottommargin
+  leftmargin
+  background
+  bgcolor
+  text
+  link
+  vlink
+  alink
+
+frame, iframe
+  marginheight
+  marginwidth
+
+font
+  face
+  color
+  size
+
+table
+  cellspacing
+  cellpadding
+  hspace
+  vspace
+  height
+  width
+  bordercolor
+  border
+
+col
+  width
+
+tr
+  height
+
+td, th
+  width
+  height
+
+caption, thead, tbody, tfoot, tr, td, and th
+  align
+
+table, thead, tbody, tfoot, tr, td, or th
+  background
+  bgcolor
+
+(quirks mode) th, td
+  nowrap
+
+hr
+  color
+  noshade
+  size
+  width
+
+legend
+  align
+
+applet, embed, iframe, img, input[type=image i], object
+  hspace
+  vspace
+
+img, input[type=image i], object
+  border
+
+applet, embed, iframe, img, input[type=image i], object, video
+  width
+  height
+
+*/
+
+/*
+
+Extra
+  ol > li
+    https://html.spec.whatwg.org/multipage/semantics.html#ordinal-value
+  col
+    span
+  colgroup (if not col child)
+    span
+  td, th
+    colspan
+    rowspan
+
+  :computed-value(text-align is initial) > th {
+    text-align: center;
+  }
+
+  https://html.spec.whatwg.org/multipage/rendering.html#rendered-legend
+
+*/
+
diff --git a/resources/quirks-mode.css b/resources/quirks-mode.css
new file mode 100644
index 00000000000..4ba71bb6392
--- /dev/null
+++ b/resources/quirks-mode.css
@@ -0,0 +1,33 @@
+/*
+
+https://html.spec.whatwg.org/multipage/rendering.html#flow-content-3
+
+> In quirks mode, the following rules are also expected to apply:
+
+*/
+
+@namespace url(http://www.w3.org/1999/xhtml);
+
+
+form { margin-bottom: 1em; }
+
+
+table {
+  font-weight: initial;
+  font-style: initial;
+  font-variant: initial;
+  font-size: initial;
+  line-height: initial;
+  white-space: initial;
+  text-align: initial;
+}
+
+
+/* FIXME: https://html.spec.whatwg.org/multipage/rendering.html#margin-collapsing-quirks */
+
+
+input:not([type=image]), textarea { box-sizing: border-box; }
+
+
+img[align=left i] { margin-right: 3px; }
+img[align=right i] { margin-left: 3px; }
diff --git a/resources/quotes.css b/resources/quotes.css
new file mode 100644
index 00000000000..2b1b7470b16
--- /dev/null
+++ b/resources/quotes.css
@@ -0,0 +1,190 @@
+/*
+
+https://html.spec.whatwg.org/multipage/rendering.html#quotes
+
+> This block is automatically generated from the Unicode Common Locale Data Repository.
+> http://cldr.unicode.org/
+>
+> User agents are expected to use either the block [from the spec]
+> (which will be regularly updated)
+> or to automatically generate their own copy directly from the source material.
+> The language codes are derived from the CLDR file names.
+> The quotes are derived from the delimiter blocks,
+> with fallback handled as specified in the CLDR documentation.
+
+*/
+
+@namespace url(http://www.w3.org/1999/xhtml);
+
+
+:root                                                         { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(af),       :not(:lang(af)) > :lang(af)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(agq),      :not(:lang(agq)) > :lang(agq)           { quotes: '\201e' '\201d' '\201a' '\2019' } /* „ ” ‚ ’ */
+:root:lang(ak),       :not(:lang(ak)) > :lang(ak)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(am),       :not(:lang(am)) > :lang(am)             { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(ar),       :not(:lang(ar)) > :lang(ar)             { quotes: '\201d' '\201c' '\2019' '\2018' } /* ” “ ’ ‘ */
+:root:lang(asa),      :not(:lang(asa)) > :lang(asa)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ast),      :not(:lang(ast)) > :lang(ast)           { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(az),       :not(:lang(az)) > :lang(az)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(az-Cyrl),  :not(:lang(az-Cyrl)) > :lang(az-Cyrl)   { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(bas),      :not(:lang(bas)) > :lang(bas)           { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */
+:root:lang(bem),      :not(:lang(bem)) > :lang(bem)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(bez),      :not(:lang(bez)) > :lang(bez)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(bg),       :not(:lang(bg)) > :lang(bg)             { quotes: '\201e' '\201c' '\201e' '\201c' } /* „ “ „ “ */
+:root:lang(bm),       :not(:lang(bm)) > :lang(bm)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(bn),       :not(:lang(bn)) > :lang(bn)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(br),       :not(:lang(br)) > :lang(br)             { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(brx),      :not(:lang(brx)) > :lang(brx)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(bs),       :not(:lang(bs)) > :lang(bs)             { quotes: '\201e' '\201c' '\2018' '\2019' } /* „ “ ‘ ’ */
+:root:lang(bs-Cyrl),  :not(:lang(bs-Cyrl)) > :lang(bs-Cyrl)   { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(ca),       :not(:lang(ca)) > :lang(ca)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(cgg),      :not(:lang(cgg)) > :lang(cgg)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(chr),      :not(:lang(chr)) > :lang(chr)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(cs),       :not(:lang(cs)) > :lang(cs)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(cy),       :not(:lang(cy)) > :lang(cy)             { quotes: '\2018' '\2019' '\201c' '\201d' } /* ‘ ’ “ ” */
+:root:lang(da),       :not(:lang(da)) > :lang(da)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(dav),      :not(:lang(dav)) > :lang(dav)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(de),       :not(:lang(de)) > :lang(de)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(de-CH),    :not(:lang(de-CH)) > :lang(de-CH)       { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(dje),      :not(:lang(dje)) > :lang(dje)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(dsb),      :not(:lang(dsb)) > :lang(dsb)           { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(dua),      :not(:lang(dua)) > :lang(dua)           { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */
+:root:lang(dyo),      :not(:lang(dyo)) > :lang(dyo)           { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(dz),       :not(:lang(dz)) > :lang(dz)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ebu),      :not(:lang(ebu)) > :lang(ebu)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ee),       :not(:lang(ee)) > :lang(ee)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(el),       :not(:lang(el)) > :lang(el)             { quotes: '\00ab' '\00bb' '\0022' '\0022' } /* « » " " */
+:root:lang(en),       :not(:lang(en)) > :lang(en)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(es),       :not(:lang(es)) > :lang(es)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(et),       :not(:lang(et)) > :lang(et)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(eu),       :not(:lang(eu)) > :lang(eu)             { quotes: '\0022' '\0022' '\0022' '\0022' } /* " " " " */
+:root:lang(ewo),      :not(:lang(ewo)) > :lang(ewo)           { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(fa),       :not(:lang(fa)) > :lang(fa)             { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(ff),       :not(:lang(ff)) > :lang(ff)             { quotes: '\201e' '\201d' '\201a' '\2019' } /* „ ” ‚ ’ */
+:root:lang(fi),       :not(:lang(fi)) > :lang(fi)             { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */
+:root:lang(fil),      :not(:lang(fil)) > :lang(fil)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(fr),       :not(:lang(fr)) > :lang(fr)             { quotes: '\00ab' '\00bb' '\00ab' '\00bb' } /* « » « » */
+:root:lang(fr-CA),    :not(:lang(fr-CA)) > :lang(fr-CA)       { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(fr-CH),    :not(:lang(fr-CH)) > :lang(fr-CH)       { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(ga),       :not(:lang(ga)) > :lang(ga)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(gd),       :not(:lang(gd)) > :lang(gd)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(gl),       :not(:lang(gl)) > :lang(gl)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(gsw),      :not(:lang(gsw)) > :lang(gsw)           { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(gu),       :not(:lang(gu)) > :lang(gu)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(guz),      :not(:lang(guz)) > :lang(guz)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ha),       :not(:lang(ha)) > :lang(ha)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(he),       :not(:lang(he)) > :lang(he)             { quotes: '\05f4' '\05f4' '\05f3' '\05f3' } /* ״ ״ ׳ ׳ */
+:root:lang(hi),       :not(:lang(hi)) > :lang(hi)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(hr),       :not(:lang(hr)) > :lang(hr)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(hsb),      :not(:lang(hsb)) > :lang(hsb)           { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(hu),       :not(:lang(hu)) > :lang(hu)             { quotes: '\201e' '\201d' '\00bb' '\00ab' } /* „ ” » « */
+:root:lang(hy),       :not(:lang(hy)) > :lang(hy)             { quotes: '\00ab' '\00bb' '\00ab' '\00bb' } /* « » « » */
+:root:lang(id),       :not(:lang(id)) > :lang(id)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ig),       :not(:lang(ig)) > :lang(ig)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(is),       :not(:lang(is)) > :lang(is)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(it),       :not(:lang(it)) > :lang(it)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(ja),       :not(:lang(ja)) > :lang(ja)             { quotes: '\300c' '\300d' '\300e' '\300f' } /* 「 」 『 』 */
+:root:lang(jgo),      :not(:lang(jgo)) > :lang(jgo)           { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(jmc),      :not(:lang(jmc)) > :lang(jmc)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ka),       :not(:lang(ka)) > :lang(ka)             { quotes: '\201e' '\201c' '\00ab' '\00bb' } /* „ “ « » */
+:root:lang(kab),      :not(:lang(kab)) > :lang(kab)           { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(kam),      :not(:lang(kam)) > :lang(kam)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(kde),      :not(:lang(kde)) > :lang(kde)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(kea),      :not(:lang(kea)) > :lang(kea)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(khq),      :not(:lang(khq)) > :lang(khq)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ki),       :not(:lang(ki)) > :lang(ki)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(kk),       :not(:lang(kk)) > :lang(kk)             { quotes: '\201c' '\0022' '\2018' '\2019' } /* “ " ‘ ’ */
+:root:lang(kkj),      :not(:lang(kkj)) > :lang(kkj)           { quotes: '\00ab' '\00bb' '\2039' '\203a' } /* « » ‹ › */
+:root:lang(kln),      :not(:lang(kln)) > :lang(kln)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(km),       :not(:lang(km)) > :lang(km)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(kn),       :not(:lang(kn)) > :lang(kn)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ko),       :not(:lang(ko)) > :lang(ko)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ksb),      :not(:lang(ksb)) > :lang(ksb)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ksf),      :not(:lang(ksf)) > :lang(ksf)           { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */
+:root:lang(ky),       :not(:lang(ky)) > :lang(ky)             { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */
+:root:lang(lag),      :not(:lang(lag)) > :lang(lag)           { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */
+:root:lang(lb),       :not(:lang(lb)) > :lang(lb)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(lg),       :not(:lang(lg)) > :lang(lg)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ln),       :not(:lang(ln)) > :lang(ln)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(lo),       :not(:lang(lo)) > :lang(lo)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(lt),       :not(:lang(lt)) > :lang(lt)             { quotes: '\201e' '\201c' '\201e' '\201c' } /* „ “ „ “ */
+:root:lang(lu),       :not(:lang(lu)) > :lang(lu)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(luo),      :not(:lang(luo)) > :lang(luo)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(luy),      :not(:lang(luy)) > :lang(luy)           { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(lv),       :not(:lang(lv)) > :lang(lv)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mas),      :not(:lang(mas)) > :lang(mas)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mer),      :not(:lang(mer)) > :lang(mer)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mfe),      :not(:lang(mfe)) > :lang(mfe)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mg),       :not(:lang(mg)) > :lang(mg)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(mgo),      :not(:lang(mgo)) > :lang(mgo)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mk),       :not(:lang(mk)) > :lang(mk)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(ml),       :not(:lang(ml)) > :lang(ml)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mn),       :not(:lang(mn)) > :lang(mn)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mr),       :not(:lang(mr)) > :lang(mr)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ms),       :not(:lang(ms)) > :lang(ms)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mt),       :not(:lang(mt)) > :lang(mt)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(mua),      :not(:lang(mua)) > :lang(mua)           { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(my),       :not(:lang(my)) > :lang(my)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(naq),      :not(:lang(naq)) > :lang(naq)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(nb),       :not(:lang(nb)) > :lang(nb)             { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */
+:root:lang(nd),       :not(:lang(nd)) > :lang(nd)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ne),       :not(:lang(ne)) > :lang(ne)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(nl),       :not(:lang(nl)) > :lang(nl)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(nmg),      :not(:lang(nmg)) > :lang(nmg)           { quotes: '\201e' '\201d' '\00ab' '\00bb' } /* „ ” « » */
+:root:lang(nn),       :not(:lang(nn)) > :lang(nn)             { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */
+:root:lang(nnh),      :not(:lang(nnh)) > :lang(nnh)           { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(nus),      :not(:lang(nus)) > :lang(nus)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(nyn),      :not(:lang(nyn)) > :lang(nyn)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(pa),       :not(:lang(pa)) > :lang(pa)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(pl),       :not(:lang(pl)) > :lang(pl)             { quotes: '\201e' '\201d' '\00ab' '\00bb' } /* „ ” « » */
+:root:lang(pt),       :not(:lang(pt)) > :lang(pt)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(pt-PT),    :not(:lang(pt-PT)) > :lang(pt-PT)       { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(rn),       :not(:lang(rn)) > :lang(rn)             { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */
+:root:lang(ro),       :not(:lang(ro)) > :lang(ro)             { quotes: '\201c' '\201d' '\00ab' '\00bb' } /* “ ” « » */
+:root:lang(rof),      :not(:lang(rof)) > :lang(rof)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ru),       :not(:lang(ru)) > :lang(ru)             { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */
+:root:lang(rw),       :not(:lang(rw)) > :lang(rw)             { quotes: '\00ab' '\00bb' '\2018' '\2019' } /* « » ‘ ’ */
+:root:lang(rwk),      :not(:lang(rwk)) > :lang(rwk)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(saq),      :not(:lang(saq)) > :lang(saq)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(sbp),      :not(:lang(sbp)) > :lang(sbp)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(seh),      :not(:lang(seh)) > :lang(seh)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ses),      :not(:lang(ses)) > :lang(ses)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(sg),       :not(:lang(sg)) > :lang(sg)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(shi),      :not(:lang(shi)) > :lang(shi)           { quotes: '\00ab' '\00bb' '\201e' '\201d' } /* « » „ ” */
+:root:lang(shi-Latn), :not(:lang(shi-Latn)) > :lang(shi-Latn) { quotes: '\00ab' '\00bb' '\201e' '\201d' } /* « » „ ” */
+:root:lang(si),       :not(:lang(si)) > :lang(si)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(sk),       :not(:lang(sk)) > :lang(sk)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(sl),       :not(:lang(sl)) > :lang(sl)             { quotes: '\201e' '\201c' '\201a' '\2018' } /* „ “ ‚ ‘ */
+:root:lang(sn),       :not(:lang(sn)) > :lang(sn)             { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */
+:root:lang(so),       :not(:lang(so)) > :lang(so)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(sq),       :not(:lang(sq)) > :lang(sq)             { quotes: '\00ab' '\00bb' '\201c' '\201d' } /* « » “ ” */
+:root:lang(sr),       :not(:lang(sr)) > :lang(sr)             { quotes: '\201e' '\201c' '\2018' '\2018' } /* „ “ ‘ ‘ */
+:root:lang(sr-Latn),  :not(:lang(sr-Latn)) > :lang(sr-Latn)   { quotes: '\201e' '\201c' '\2018' '\2018' } /* „ “ ‘ ‘ */
+:root:lang(sv),       :not(:lang(sv)) > :lang(sv)             { quotes: '\201d' '\201d' '\2019' '\2019' } /* ” ” ’ ’ */
+:root:lang(sw),       :not(:lang(sw)) > :lang(sw)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(swc),      :not(:lang(swc)) > :lang(swc)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ta),       :not(:lang(ta)) > :lang(ta)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(te),       :not(:lang(te)) > :lang(te)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(teo),      :not(:lang(teo)) > :lang(teo)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(th),       :not(:lang(th)) > :lang(th)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(ti-ER),    :not(:lang(ti-ER)) > :lang(ti-ER)       { quotes: '\2018' '\2019' '\201c' '\201d' } /* ‘ ’ “ ” */
+:root:lang(to),       :not(:lang(to)) > :lang(to)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(tr),       :not(:lang(tr)) > :lang(tr)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(twq),      :not(:lang(twq)) > :lang(twq)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(tzm),      :not(:lang(tzm)) > :lang(tzm)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(uk),       :not(:lang(uk)) > :lang(uk)             { quotes: '\00ab' '\00bb' '\201e' '\201c' } /* « » „ “ */
+:root:lang(ur),       :not(:lang(ur)) > :lang(ur)             { quotes: '\201d' '\201c' '\2019' '\2018' } /* ” “ ’ ‘ */
+:root:lang(ur-IN),    :not(:lang(ur-IN)) > :lang(ur-IN)       { quotes: '\0022' '\0022' '\0027' '\0027' } /* " " ' ' */
+:root:lang(uz),       :not(:lang(uz)) > :lang(uz)             { quotes: '\0022' '\0022' '\0027' '\0027' } /* " " ' ' */
+:root:lang(uz-Cyrl),  :not(:lang(uz-Cyrl)) > :lang(uz-Cyrl)   { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(vai),      :not(:lang(vai)) > :lang(vai)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(vai-Latn), :not(:lang(vai-Latn)) > :lang(vai-Latn) { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(vi),       :not(:lang(vi)) > :lang(vi)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(vun),      :not(:lang(vun)) > :lang(vun)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(xog),      :not(:lang(xog)) > :lang(xog)           { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(yav),      :not(:lang(yav)) > :lang(yav)           { quotes: '\00ab' '\00bb' '\00ab' '\00bb' } /* « » « » */
+:root:lang(yo),       :not(:lang(yo)) > :lang(yo)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(zgh),      :not(:lang(zgh)) > :lang(zgh)           { quotes: '\00ab' '\00bb' '\201e' '\201d' } /* « » „ ” */
+:root:lang(zh),       :not(:lang(zh)) > :lang(zh)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
+:root:lang(zh-Hant),  :not(:lang(zh-Hant)) > :lang(zh-Hant)   { quotes: '\300c' '\300d' '\300e' '\300f' } /* 「 」 『 』 */
+:root:lang(zu),       :not(:lang(zu)) > :lang(zu)             { quotes: '\201c' '\201d' '\2018' '\2019' } /* “ ” ‘ ’ */
diff --git a/resources/servo.css b/resources/servo.css
new file mode 100644
index 00000000000..cdeff0c0ff0
--- /dev/null
+++ b/resources/servo.css
@@ -0,0 +1,12 @@
+input                   { background: white; min-height: 1.0em; padding: 0em; padding-left: 0.25em; padding-right: 0.25em; border: solid lightgrey 1px; color: black; white-space: nowrap; }
+input[type="button"],
+input[type="submit"],
+input[type="reset"]     { background: lightgrey; border-top: solid 1px #EEEEEE; border-left: solid 1px #CCCCCC; border-right: solid 1px #999999; border-bottom: solid 1px #999999; text-align: center; vertical-align: middle; color: black; }
+input[type="hidden"]    { display: none !important }
+input[type="checkbox"],
+input[type="radio"]     { font-family: monospace !important; border: none !important; background: transparent; }
+
+input[type="checkbox"]::before { content: "[ ]"; padding: 0; }
+input[type="checkbox"][checked]::before { content: "[✓]"; }
+input[type="radio"]::before { content: "( )"; padding: 0; }
+input[type="radio"][checked]::before { content: "(●)"; }
diff --git a/resources/user-agent.css b/resources/user-agent.css
index 209bafa4c2e..8ae8f5a5960 100644
--- a/resources/user-agent.css
+++ b/resources/user-agent.css
@@ -1,130 +1,276 @@
-html, address,
-blockquote,
-body, div,
-dt, fieldset, form,
-frame, frameset,
-h1, h2, h3, h4,
-h5, h6, noframes,
-center, dir,
-hr, menu, pre       { display: block; unicode-bidi: embed }
-    head, noscript  { display: none }
-    table           { display: table }
-    tr              { display: table-row }
-    thead           { display: table-header-group }
-    tbody           { display: table-row-group }
-    tfoot           { display: table-footer-group }
-    col             { display: table-column }
-    colgroup        { display: table-column-group }
-    td, th          { display: table-cell }
-    caption         { display: table-caption }
-    th              { font-weight: bolder; text-align: center }
-    caption         { text-align: center }
-    body            { margin: 8px }
-    h1              { font-size: 2em; margin: .67em 0 }
-    h2              { font-size: 1.5em; margin: .75em 0 }
-    h3              { font-size: 1.17em; margin: .83em 0 }
-h4,
-blockquote,
-fieldset, dir,
-menu                { margin: 1.12em 0 }
-    h5              { font-size: .83em; margin: 1.5em 0 }
-    h6              { font-size: .75em; margin: 1.67em 0 }
-h1, h2, h3, h4,
-h5, h6, b,
-    strong          { font-weight: bolder }
-    blockquote      { margin-left: 40px; margin-right: 40px }
-i, cite, em,
-    var, address    { font-style: italic }
-pre, tt, code,
-    kbd, samp       { font-family: monospace }
-    pre             { white-space: pre }
-button, textarea,
-    input, select   { display: inline-block }
-    big             { font-size: 1.17em }
-    small, sub, sup { font-size: .83em }
-    sub             { vertical-align: sub }
-    sup             { vertical-align: super }
-    table           { border-spacing: 2px; }
-thead, tbody,
-    tfoot           { vertical-align: middle }
-    td, th, tr      { vertical-align: inherit }
-    s, strike, del  { text-decoration: line-through }
-    hr              { border: 1px inset }
-
-/* lists */
-dd                  { display: block; margin-left: 40px }
-p, dl, multicol     { display: block; margin: 1em 0 }
-ul                  { display: block; list-style-type: disc;
-                      margin: 1em 0; padding-left: 40px }
-
-ol                  { display: block; list-style-type: decimal;
-                      margin: 1em 0; padding-left: 40px }
-
-li                  { display: list-item }
-
-/* nested lists have no top/bottom margins */
-ul ul, ul ol, ul dl,
-ol ul, ol ol, ol dl,
-dl ul, dl ol, dl dl { margin-top: 0; margin-bottom: 0 }
-
-/* 2 deep unordered lists use a circle */
-ol ul,   ul ul      { list-style-type: circle; }
-
-/* 3 deep (or more) unordered lists use a square */
-ol ol ul, ol ul ul,
-ul ol ul, ul ul ul  { list-style-type: square; }
-
-/* The type attribute on ol and ul elements */
-ul[type="disc"]     { list-style-type: disc; }
-ul[type="circle"]   { list-style-type: circle; }
-ul[type="square"]   { list-style-type: square; }
-ol[type="1"]        { list-style-type: decimal; }
-ol[type="a"]        { list-style-type: lower-alpha; }
-ol[type="A"]        { list-style-type: upper-alpha; }
-ol[type="i"]        { list-style-type: lower-roman; }
-ol[type="I"]        { list-style-type: upper-roman; }
-
-u, ins              { text-decoration: underline }
-br:before           { content: "\A"; white-space: pre }
-
-center              { text-align: center }
-a:link,
-a:visited,
-area:link,
-area:visited,
-link:link,
-link:visited        { text-decoration: underline }
-:focus              { outline: thin dotted invert }
-
-/* Begin bidirectionality settings (do not change) */
-BDO[DIR="ltr"]      { direction: ltr; unicode-bidi: bidi-override }
-BDO[DIR="rtl"]      { direction: rtl; unicode-bidi: bidi-override }
-
-*[DIR="ltr"]        { direction: ltr; unicode-bidi: embed }
-*[DIR="rtl"]        { direction: rtl; unicode-bidi: embed }
-
-@media print {
-h1                  { page-break-before: always }
-h1, h2, h3,
-h4, h5, h6          { page-break-after: avoid }
-ul, ol, dl          { page-break-before: avoid }
-}
-
-/* Servo additions */
-a:link,
-area:link,
-link:link               { color: blue }
-script                  { display: none }
-style                   { display: none }
-input                   { background: white; min-height: 1.0em; padding: 0em; padding-left: 0.25em; padding-right: 0.25em; border: solid lightgrey 1px; color: black; white-space: nowrap; }
-input[type="button"],
-input[type="submit"],
-input[type="reset"]     { background: lightgrey; border-top: solid 1px #EEEEEE; border-left: solid 1px #CCCCCC; border-right: solid 1px #999999; border-bottom: solid 1px #999999; text-align: center; vertical-align: middle; color: black; }
-input[type="hidden"]    { display: none !important }
-input[type="checkbox"],
-input[type="radio"]     { font-family: monospace !important; border: none !important; background: transparent; }
-
-input[type="checkbox"]::before { content: "[ ]"; padding: 0; }
-input[type="checkbox"][checked]::before { content: "[✓]"; }
-input[type="radio"]::before { content: "( )"; padding: 0; }
-input[type="radio"][checked]::before { content: "(●)"; }
+/*
+https://html.spec.whatwg.org/multipage/rendering.html#form-controls
+*/
+
+@namespace url(http://www.w3.org/1999/xhtml);
+
+/*
+FIXME: Uncomment this when :lang() is supported, or do something equivalent.
+@import url(quotes.css);
+*/
+
+[hidden], area, base, basefont, datalist, head, link, menu[type=popup i], meta,
+noembed, noframes, param, rp, script, source, style, template, track, title {
+  display: none;
+}
+
+embed[hidden] { display: inline; height: 0; width: 0; }
+
+/* FIXME: only if scripting is enabled */
+noscript { display: none !important; }
+
+input[type=hidden i] { display: none !important; }
+
+
+html, body { display: block; }
+
+body { margin: 8px; }
+
+
+address, blockquote, center, div, figure, figcaption, footer, form, header, hr,
+legend, listing, main, p, plaintext, pre, summary, xmp {
+  display: block;
+}
+
+blockquote, figure, listing, p, plaintext, pre, xmp {
+  margin-top: 1em; margin-bottom: 1em;
+}
+
+blockquote, figure { margin-left: 40px; margin-right: 40px; }
+
+address { font-style: italic; }
+listing, plaintext, pre, xmp {
+  font-family: monospace; white-space: pre;
+}
+
+dialog:not([open]) { display: none; }
+dialog {
+  position: absolute;
+  left: 0; right: 0;
+  /* FIXME: support fit-content */
+  width: fit-content;
+  height: fit-content;
+  margin: auto;
+  border: solid;
+  padding: 1em;
+  background: white;
+  color: black;
+}
+/* FIXME: support ::backdrop */
+dialog::backdrop {
+  position: fixed;
+  top: 0; right: 0; bottom: 0; left: 0;
+  background: rgba(0,0,0,0.1);
+}
+
+/* for small devices, modal dialogs go full-screen */
+@media screen and (max-width: 540px) {
+  /* FIXME: support :modal */
+  dialog:modal {
+    top: 0;
+    width: auto;
+    margin: 1em;
+  }
+}
+
+
+cite, dfn, em, i, var { font-style: italic; }
+b, strong { font-weight: bolder; }
+code, kbd, samp, tt { font-family: monospace; }
+big { font-size: larger; }
+small { font-size: smaller; }
+
+sub { vertical-align: sub; }
+sup { vertical-align: super; }
+sub, sup { line-height: normal; font-size: smaller; }
+
+ruby { display: ruby; }
+rt { display: ruby-text; }
+
+:link { color: #0000EE; }
+:visited { color: #551A8B; }
+:link, :visited { text-decoration: underline; }
+a:link[rel~=help], a:visited[rel~=help],
+area:link[rel~=help], area:visited[rel~=help] { cursor: help; }
+
+:focus { outline: thin dotted; }  /* FIXME: 'outline: auto' ? */
+
+mark { background: yellow; color: black; }
+
+abbr[title], acronym[title] { text-decoration: dotted underline; }
+ins, u { text-decoration: underline; }
+del, s, strike { text-decoration: line-through; }
+blink { text-decoration: blink; }
+
+q::before { content: open-quote; }
+q::after { content: close-quote; }
+
+/*br { display-outside: newline; } /* this also has bidi implications */
+br::before { content: "\A"; white-space: pre }
+
+nobr { white-space: nowrap; }
+wbr { display-outside: break-opportunity; } /* this also has bidi implications */
+nobr wbr { white-space: normal; }
+
+
+[dir]:dir(ltr), bdi:dir(ltr), input[type=tel]:dir(ltr) { direction: ltr; }
+[dir]:dir(rtl), bdi:dir(rtl) { direction: rtl; }
+
+address, blockquote, center, div, figure, figcaption, footer, form, header, hr,
+legend, listing, main, p, plaintext, pre, summary, xmp, article, aside, h1, h2,
+h3, h4, h5, h6, hgroup, nav, section, table, caption, colgroup, col, thead,
+tbody, tfoot, tr, td, th, dir, dd, dl, dt, menu, ol, ul, li, bdi, output,
+[dir=ltr i], [dir=rtl i], [dir=auto i] {
+  unicode-bidi: isolate;
+}
+
+bdo, bdo[dir] { unicode-bidi: isolate-override; }
+
+textarea[dir=auto i], pre[dir=auto i] { unicode-bidi: plaintext; }
+
+
+article, aside, h1, h2, h3, h4, h5, h6, hgroup, nav, section {
+  display: block;
+}
+
+h1 { margin-top: 0.67em; margin-bottom: 0.67em; font-size: 2.00em; font-weight: bold; }
+h2 { margin-top: 0.83em; margin-bottom: 0.83em; font-size: 1.50em; font-weight: bold; }
+h3 { margin-top: 1.00em; margin-bottom: 1.00em; font-size: 1.17em; font-weight: bold; }
+h4 { margin-top: 1.33em; margin-bottom: 1.33em; font-size: 1.00em; font-weight: bold; }
+h5 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; font-weight: bold; }
+h6 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; font-weight: bold; }
+
+:matches(article, aside, nav, section) h1 { margin-top: 0.83em; margin-bottom: 0.83em; font-size: 1.50em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) h1 { margin-top: 1.00em; margin-bottom: 1.00em; font-size: 1.17em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) h1 { margin-top: 1.33em; margin-bottom: 1.33em; font-size: 1.00em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) h1 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) h1 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; }
+
+:matches(article, aside, nav, section) hgroup > h1 ~ h2 { margin-top: 1.00em; margin-bottom: 1.00em; font-size: 1.17em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) hgroup > h1 ~ h2 { margin-top: 1.33em; margin-bottom: 1.33em; font-size: 1.00em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) hgroup > h1 ~ h2 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) hgroup > h1 ~ h2 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; }
+
+:matches(article, aside, nav, section) hgroup > h1 ~ h3 { margin-top: 1.33em; margin-bottom: 1.33em; font-size: 1.00em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) hgroup > h1 ~ h3 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) :matches(article, aside, nav, section) hgroup > h1 ~ h3 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; }
+
+:matches(article, aside, nav, section) hgroup > h1 ~ h4 { margin-top: 1.67em; margin-bottom: 1.67em; font-size: 0.83em; }
+:matches(article, aside, nav, section) :matches(article, aside, nav, section) hgroup > h1 ~ h4 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; }
+
+:matches(article, aside, nav, section) hgroup > h1 ~ h5 { margin-top: 2.33em; margin-bottom: 2.33em; font-size: 0.67em; }
+
+
+dir, dd, dl, dt, menu, ol, ul { display: block; }
+li { display: list-item; }
+
+dir, dl, menu, ol, ul { margin-top: 1em; margin-bottom: 1em; }
+
+:matches(dir, dl, menu, ol, ul) :matches(dir, dl, menu, ol, ul) {
+  margin-top: 0; margin-bottom: 0;
+}
+
+dd { margin-left: 40px; } /* FIXME: use margin-inline-start when supported */
+dir, menu, ol, ul { padding-left: 40px; } /* FIXME: use padding-inline-start when supported */
+
+ol { list-style-type: decimal; }
+
+dir, menu, ul { list-style-type: disc; }
+
+:matches(dir, menu, ol, ul) :matches(dir, menu, ul) {
+  list-style-type: circle;
+}
+
+:matches(dir, menu, ol, ul) :matches(dir, menu, ol, ul) :matches(dir, menu, ul) {
+  list-style-type: square;
+}
+
+
+table { display: table; }
+caption { display: table-caption; }
+colgroup, colgroup[hidden] { display: table-column-group; }
+col, col[hidden] { display: table-column; }
+thead, thead[hidden] { display: table-header-group; }
+tbody, tbody[hidden] { display: table-row-group; }
+tfoot, tfoot[hidden] { display: table-footer-group; }
+tr, tr[hidden] { display: table-row; }
+td, th, td[hidden], th[hidden] { display: table-cell; }
+
+colgroup[hidden], col[hidden], thead[hidden], tbody[hidden],
+tfoot[hidden], tr[hidden], td[hidden], th[hidden] {
+  visibility: collapse;
+}
+
+table {
+  box-sizing: border-box;
+  border-spacing: 2px;
+  border-collapse: separate;
+  text-indent: initial;
+}
+td, th { padding: 1px; }
+th { font-weight: bold; }
+
+thead, tbody, tfoot, table > tr { vertical-align: middle; }
+tr, td, th { vertical-align: inherit; }
+
+
+table, td, th { border-color: gray; }
+thead, tbody, tfoot, tr { border-color: inherit; }
+table:matches(
+  [rules=none i], [rules=groups i], [rules=rows i],
+  [rules=cols i], [rules=all i],
+  [frame=void i], [frame=above i], [frame=below i],
+  [frame=hsides i], [frame=lhs i], [frame=rhs i],
+  [frame=vsides i], [frame=box i], [frame=border i]
+),
+table:matches(
+  [rules=none i], [rules=groups i], [rules=rows i],
+  [rules=cols i], [rules=all i]
+) > tr > :matches(td, th),
+table:matches(
+  [rules=none i], [rules=groups i], [rules=rows i],
+  [rules=cols i], [rules=all i]
+) > :matches(thead, tbody, tfoot) > tr > :matches(td, th) {
+  border-color: black;
+}
+
+
+:matches(table, thead, tbody, tfoot, tr) > form {
+  display: none !important;
+}
+
+
+input, select, option, optgroup, button, textarea, keygen {
+  text-indent: initial;
+}
+
+textarea { white-space: pre-wrap; }
+
+input[type="radio"], input[type="checkbox"], input[type="reset"], input[type="button"],
+input[type="submit"], select, button {
+  box-sizing: border-box;
+}
+
+
+hr { color: gray; border-style: inset; border-width: 1px; margin: 0.5em auto; }
+
+
+fieldset {
+  display: block; /* https://www.w3.org/Bugs/Public/show_bug.cgi?id=27018 */
+  margin-left: 2px; margin-right: 2px;
+  border: groove 2px;
+  border-color: ThreeDFace; /* FIXME: system color */
+  padding: 0.35em 0.625em 0.75em;
+  min-width: min-content;
+}
+
+legend {
+  padding-left: 2px; padding-right: 2px;
+}
+
+iframe:not([seamless]) { border: 2px inset; }
+iframe[seamless] { display: block; }
+video { object-fit: contain; }
+
+
+textarea { white-space: pre-wrap; }