add(styles/github-dark): github's dark colorscheme for chroma (#653)

styles/github-dark.go

@@ -0,0 +1,68 @@
+package styles
+
+import (
+	"fmt"
+
+	"github.com/alecthomas/chroma/v2"
+)
+
+var (
+	// colors used from https://github.com/primer/primitives
+	ghRed2      = "#ffa198"
+	ghRed3      = "#ff7b72"
+	ghRed9      = "#490202"
+	ghOrange3   = "#f0883e"
+	ghOrange2   = "#ffa657"
+	ghGreen1    = "#7ee787"
+	ghGreen2    = "#56d364"
+	ghBlue1     = "#a5d6ff"
+	ghBlue2     = "#79c0ff"
+	ghPurple2   = "#d2a8ff"
+	ghGray3     = "#8b949e"
+	ghFgSubtle  = "#6e7681"
+	ghFgDefault = "#c9d1d9"
+	ghBgDefault = "#0d1117"
+	ghDangerFg  = "#f85149"
+)
+
+// GitHub Dark style.
+var GitHubDark = Register(chroma.MustNewStyle("github-dark", chroma.StyleEntries{
+	chroma.Comment:             "italic " + ghGray3,
+	chroma.CommentPreproc:      "bold " + ghGray3,
+	chroma.CommentSpecial:      "bold italic " + ghGray3,
+	chroma.Error:               ghDangerFg,
+	chroma.GenericDeleted:      fmt.Sprintf("bg:%s %s", ghRed9, ghRed2),
+	chroma.Generic:             ghFgDefault,
+	chroma.GenericEmph:         "italic " + ghFgDefault,
+	chroma.GenericError:        ghRed2,
+	chroma.GenericHeading:      ghBlue2,
+	chroma.GenericInserted:     fmt.Sprintf("bg:%s %s", ghGreen2, ghGreen1),
+	chroma.GenericOutput:       ghGray3,
+	chroma.GenericPrompt:       ghGray3,
+	chroma.GenericStrong:       "bold",
+	chroma.GenericSubheading:   ghBlue2,
+	chroma.GenericTraceback:    ghRed2,
+	chroma.GenericUnderline:    "underline",
+	chroma.Keyword:             "bold " + ghRed3,
+	chroma.KeywordConstant:     "bold " + ghBlue2,
+	chroma.Literal:             ghBlue1,
+	chroma.LiteralDate:         ghBlue2,
+	chroma.LiteralStringRegex:  ghBlue2,
+	chroma.LiteralStringAffix:  ghBlue2,
+	chroma.LiteralStringEscape: ghBlue2,
+	chroma.Name:                ghFgDefault,
+	chroma.NameProperty:        ghBlue2,
+	chroma.NameClass:           ghOrange3,
+	chroma.NameConstant:        ghBlue2,
+	chroma.NameDecorator:       "bold " + ghPurple2,
+	chroma.NameEntity:          ghOrange2,
+	chroma.NameException:       "bold " + ghOrange3,
+	chroma.NameFunction:        "bold " + ghPurple2,
+	chroma.NameLabel:           "bold " + ghBlue2,
+	chroma.NameNamespace:       ghRed3,
+	chroma.NameTag:             ghGreen1,
+	chroma.NameVariable:        ghBlue2,
+	chroma.Operator:            "bold " + ghRed3,
+	chroma.TextWhitespace:      ghFgSubtle,
+	chroma.Background:          fmt.Sprintf("bg:%s %s", ghBgDefault, ghFgDefault),
+}))