css: Support for dark modejd/zx2c4-deployment

Modern browsers have a "dark mode" preference, which enables alternate
styles on web sites that support this.

This patch adds a dark color scheme, that is automatically activated
via a CSS @media query.

Older browsers that do not support color schemes will simply show the
light scheme, but possibly without syntax highlighting.

Note that filters that use color (such as source highlighters) and
logotypes may need to be updated to work with a black background!
See the updated files in the filters/ directory.

Signed-off-by: Samuel Lidén Borell <samuel@kodafritt.se>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 104 insertions, 44 deletions

diff --git a/filters/html-converters/md2html b/filters/html-converters/md2html
index 59f43a8..627808a 100755
--- a/filters/html-converters/md2html
+++ b/filters/html-converters/md2html
@@ -4,6 +4,11 @@ import sys
 import io
 from pygments.formatters import HtmlFormatter
 from markdown.extensions.toc import TocExtension
+
+# The dark style is automatically selected if the browser is in dark mode
+light_style='pastie'
+dark_style='monokai'
+
 sys.stdin = io.TextIOWrapper(sys.stdin.buffer, encoding='utf-8')
 sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')
 sys.stdout.write('''
@@ -283,10 +288,31 @@ div#cgit .markdown-body h1 a.toclink, div#cgit .markdown-body h2 a.toclink, div#
     background-color: transparent;
     border: none;
 }
+@media only all and (prefers-color-scheme: dark) {
+.markdown-body a.absent { color: #f33; }
+.markdown-body h1 .mini-icon-link, .markdown-body h2 .mini-icon-link, .markdown-body h3 .mini-icon-link, .markdown-body h4 .mini-icon-link, .markdown-body h5 .mini-icon-link, .markdown-body h6 .mini-icon-link { color: #eee; }
+div#cgit .markdown-body h1 a.toclink, div#cgit .markdown-body h2 a.toclink, div#cgit .markdown-body h3 a.toclink, div#cgit .markdown-body h4 a.toclink, div#cgit .markdown-body h5 a.toclink, div#cgit .markdown-body h6 a.toclink { color: #eee; }
+.markdown-body h1 { color: #eee; }
+.markdown-body h2 { border-bottom-color: #333; color: #eee; }
+.markdown-body h6 { color: #888; }
+.markdown-body hr { border-color: #333; }
+.markdown-body blockquote { border-left-color: #222; color: #888; }
+.markdown-body table th, .markdown-body table td { border-color: #333; }
+.markdown-body table tr { border-top-color: #333; background-color: #111; }
+.markdown-body table tr:nth-child(2n) { background-color: #070707; }
+.markdown-body span.frame span span { color: #ccc; }
+.markdown-body code, .markdown-body tt { border-color: #151515; background-color: #070707; }
+.markdown-body .highlight pre, .markdown-body pre { background-color: #070707; border-color: #333; }
 ''')
-sys.stdout.write(HtmlFormatter(style='pastie').get_style_defs('.highlight'))
+sys.stdout.write(HtmlFormatter(style=dark_style).get_style_defs('.highlight'))
 sys.stdout.write('''
-</style>   
+}
+@media (prefers-color-scheme: light) {
+''')
+sys.stdout.write(HtmlFormatter(style=light_style).get_style_defs('.highlight'))
+sys.stdout.write('''
+}
+</style>
 ''')
 sys.stdout.write("<div class='markdown-body'>")
 sys.stdout.flush()
diff --git a/filters/syntax-highlighting.py b/filters/syntax-highlighting.py
index e912594..f2c0fe1 100755
--- a/filters/syntax-highlighting.py
+++ b/filters/syntax-highlighting.py
@@ -29,12 +29,16 @@ from pygments.lexers import guess_lexer
 from pygments.lexers import guess_lexer_for_filename
 from pygments.formatters import HtmlFormatter
 
+# The dark style is automatically selected if the browser is in dark mode
+light_style='pastie'
+dark_style='monokai'
 
 sys.stdin = io.TextIOWrapper(sys.stdin.buffer, encoding='utf-8', errors='replace')
 sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8', errors='replace')
 data = sys.stdin.read()
 filename = sys.argv[1]
-formatter = HtmlFormatter(style='pastie', nobackground=True)
+light_formatter = HtmlFormatter(style=light_style, nobackground=True)
+dark_formatter = HtmlFormatter(style=dark_style, nobackground=True)
 
 try:
 	lexer = guess_lexer_for_filename(filename, data)
@@ -50,6 +54,10 @@ except TypeError:
 # highlight! :-)
 # printout pygments' css definitions as well
 sys.stdout.write('<style>')
-sys.stdout.write(formatter.get_style_defs('.highlight'))
+sys.stdout.write('\n@media only all and (prefers-color-scheme: dark) {\n')
+sys.stdout.write(dark_formatter.get_style_defs('.highlight'))
+sys.stdout.write('\n}\n@media (prefers-color-scheme: light) {\n')
+sys.stdout.write(light_formatter.get_style_defs('.highlight'))
+sys.stdout.write('\n}\n')
 sys.stdout.write('</style>')
-sys.stdout.write(highlight(data, lexer, formatter, outfile=None))
+sys.stdout.write(highlight(data, lexer, light_formatter, outfile=None))
diff --git a/filters/syntax-highlighting.sh b/filters/syntax-highlighting.sh
index 840bc34..0429b0f 100755
--- a/filters/syntax-highlighting.sh
+++ b/filters/syntax-highlighting.sh
@@ -25,6 +25,20 @@
 # table.blob .kwb  { color:#830000; }
 # table.blob .kwc  { color:#000000; font-weight:bold; }
 # table.blob .kwd  { color:#010181; }
+# @media only all and (prefers-color-scheme: dark) { /* cgit addition for dark mode */
+# 	table.blob .num  { color:#ff814f; }
+# 	table.blob .esc  { color:#f60; }
+# 	table.blob .str  { color:#cc0; }
+# 	table.blob .dstr { color:#ffff7e; }
+# 	table.blob .slc  { color:#7f7c7f; }
+# 	table.blob .com  { color:#7e7c7e; }
+# 	table.blob .dir  { color:#7dff7d; }
+# 	table.blob .sym  { color:#eeeeee; }
+# 	table.blob .kwa  { color:#bb0; }
+# 	table.blob .kwb  { color:#0a0; }
+# 	table.blob .kwc  { color:#eeeeee; }
+# 	table.blob .kwd  { color:#7e7efe; }
+# }
 #
 #
 # Style definition file generated by highlight 2.6.14, http://www.andre-simon.de/
@@ -45,45 +59,57 @@
 # .hl.kwb  { color:#830000; }
 # .hl.kwc  { color:#000000; font-weight:bold; }
 # .hl.kwd  { color:#010181; }
-#
-#
-# Style definition file generated by highlight 3.8, http://www.andre-simon.de/
-#
-# body.hl { background-color:#e0eaee; }
-# pre.hl  { color:#000000; background-color:#e0eaee; font-size:10pt; font-family:'Courier New';}
-# .hl.num { color:#b07e00; }
-# .hl.esc { color:#ff00ff; }
-# .hl.str { color:#bf0303; }
-# .hl.pps { color:#818100; }
-# .hl.slc { color:#838183; font-style:italic; }
-# .hl.com { color:#838183; font-style:italic; }
-# .hl.ppc { color:#008200; }
-# .hl.opt { color:#000000; }
-# .hl.lin { color:#555555; }
-# .hl.kwa { color:#000000; font-weight:bold; }
-# .hl.kwb { color:#0057ae; }
-# .hl.kwc { color:#000000; font-weight:bold; }
-# .hl.kwd { color:#010181; }
-#
-#
-# Style definition file generated by highlight 3.13, http://www.andre-simon.de/
-#
-# body.hl { background-color:#e0eaee; }
-# pre.hl  { color:#000000; background-color:#e0eaee; font-size:10pt; font-family:'Courier New',monospace;}
-# .hl.num { color:#b07e00; }
-# .hl.esc { color:#ff00ff; }
-# .hl.str { color:#bf0303; }
-# .hl.pps { color:#818100; }
-# .hl.slc { color:#838183; font-style:italic; }
-# .hl.com { color:#838183; font-style:italic; }
-# .hl.ppc { color:#008200; }
-# .hl.opt { color:#000000; }
-# .hl.ipl { color:#0057ae; }
-# .hl.lin { color:#555555; }
-# .hl.kwa { color:#000000; font-weight:bold; }
-# .hl.kwb { color:#0057ae; }
-# .hl.kwc { color:#000000; font-weight:bold; }
-# .hl.kwd { color:#010181; }
+# @media only all and (prefers-color-scheme: dark) { /* cgit addition for dark mode */
+# 	pre.hl  { color:#eeeeee; background-color:#111; }
+# 	.hl.num  { color:#ff814f; }
+# 	.hl.esc  { color:#f60; }
+# 	.hl.str  { color:#cc0; }
+# 	.hl.dstr { color:#ffff7e; }
+# 	.hl.slc  { color:#7f7c7f; }
+# 	.hl.com  { color:#7e7c7e; }
+# 	.hl.dir  { color:#7dff7d; }
+# 	.hl.sym  { color:#eeeeee; }
+# 	.hl.line { color:#aaaaaa; }
+# 	.hl.mark { background-color:#444400; }
+# 	.hl.kwa  { color:#bb0; }
+# 	.hl.kwb  { color:#a0a; }
+# 	.hl.kwc  { color:#eeeeee; }
+# 	.hl.kwd  { color:#7e7efe; }
+# }
+#
+#
+# Style definition file generated by highlight 3.8 / 3.13 / 3.41, http://www.andre-simon.de/
+#
+# table.blob .num { color:#b07e00; }
+# table.blob .esc { color:#ff00ff; }
+# table.blob .str { color:#bf0303; }
+# table.blob .pps { color:#818100; }
+# table.blob .slc { color:#838183; font-style:italic; }
+# table.blob .com { color:#838183; font-style:italic; }
+# table.blob .ppc { color:#008200; }
+# table.blob .opt { color:#000000; }
+# table.blob .ipl { color:#0057ae; }
+# table.blob .lin { color:#555555; }
+# table.blob .kwa { color:#000000; font-weight:bold; }
+# table.blob .kwb { color:#0057ae; }
+# table.blob .kwc { color:#000000; font-weight:bold; }
+# table.blob .kwd { color:#010181; }
+# @media only all and (prefers-color-scheme: dark) { /* cgit addition for dark mode */
+# 	table.blob .num { color:#ff814f; }
+# 	table.blob .esc { color:#f60; }
+# 	table.blob .str { color:#cc0; }
+# 	table.blob .pps { color:#ffff7f; }
+# 	table.blob .slc { color:#7f7c7f; }
+# 	table.blob .com { color:#7e7c7e; }
+# 	table.blob .ppc { color:#8dd; }
+# 	table.blob .opt { color:#eeeeee; }
+# 	table.blob .ipl { color:#51a8ff; }
+# 	table.blob .lin { color:#aaaaaa; }
+# 	table.blob .kwa { color:#bb0; }
+# 	table.blob .kwb { color:#0a0; }
+# 	table.blob .kwc { color:#eeeeee; }
+# 	table.blob .kwd { color:#7e7efe; }
+# }
 #
 #
 # The following environment variables can be used to retrieve the configuration