[css-fonts-4] Begin Fonts 4 as a delta spec, to track issues.

Author: tabatkins

css-fonts-4/Overview.bs

@@ -0,0 +1,39 @@
+<pre class='metadata'>
+Title: CSS Fonts Module Level 4
+Shortname: css-fonts
+Level: 1
+Status: ED
+Group: CSSWG
+ED: https://dev.w3.org/csswg/css-fonts-4/
+No Editor: true
+Abstract: This is a delta spec over <a href="https://dev.w3.org/csswg/css-fonts-3/">CSS Fonts 3</a>, to hold issues on things we've resolved to add. It's not currently a usable spec.
+Warning: not ready
+Ignored Terms: font-palette, <named-palette-color>
+</pre>
+
+Introduction {#intro}
+=====================
+
+Intro goes here.
+
+<div class="issue">
+	Resolved at 2015 Sydney to add font-palette control.
+	<a href="https://lists.w3.org/Archives/Public/www-style/2015Feb/0211.html">Original proposal</a>.
+	Final proposal is:
+
+	1. Add a 'font-palette' property.  For now the grammar is just:
+
+		<pre class=prod><<integer>> | light | dark | <<named-palette-color>#</pre>
+
+		with <<integer>> selecting the nth palette in the font,
+		and ''light'' and ''dark'' selecting the first palette designated "light" or "dark"
+		(this is metadata that's already part of the format).
+		If there's any font fallback, the fallback fonts don't use a palette.
+	2. Add ''@palette-entries'' to ''@font-feature-values'',
+		with the name of each declaration defining a name for a particular palette color,
+		and the value being an integer for the index of that palette color.
+		<<named-palette-color>> is <code><<ident>> <<color>></code>.
+		Any palette colors not given an explicit value default to opaque black.
+		If a palette color name occurs more than once, the last one wins
+		(so you can declare a palette in a variable, and override bits as desired).
+</div>