Add Fira Code as a built-in font choice

The variable face (v6.2, OFL, licence alongside) is bundled in static/ and
declared as @font-face whenever the text or heading font is "fira"; the
stack falls back through Fira Mono, Menlo and Consolas to Courier.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

1 files changed, 13 insertions, 4 deletions

diff --git a/internal/web/theme.go b/internal/web/theme.go
index 53e48c5..676a01e 100644
--- a/internal/web/theme.go
+++ b/internal/web/theme.go
@@ -25,8 +25,8 @@ type Theme struct {
 	LinkUnderline  string `json:"link_underline"`  // always | hover | never
 	ContentStyle   string `json:"content_style"`   // card | flat
 	ContentPadding string `json:"content_padding"` // normal | compact | roomy
-	Font           string `json:"font"`            // sans | serif | mono
-	HeadingFont    string `json:"heading_font"`    // same | sans | serif | mono
+	Font           string `json:"font"`            // sans | serif | mono | fira (Fira Code, bundled in static/)
+	HeadingFont    string `json:"heading_font"`    // same | sans | serif | mono | fira
 	FontSize       string `json:"font_size"`       // small | normal | large
 	// Uploaded fonts (file uuids or ""): when set, the blog is typeset in the
 	// file and Font/HeadingFont are the stack readers see until it loads, or
@@ -176,8 +176,8 @@ func (t *Theme) normalize() {
 	t.LinkUnderline = pick(t.LinkUnderline, "always", "hover", "never")
 	t.ContentStyle = pick(t.ContentStyle, "card", "flat")
 	t.ContentPadding = pick(t.ContentPadding, "normal", "compact", "roomy")
-	t.Font = pick(t.Font, "sans", "serif", "mono")
-	t.HeadingFont = pick(t.HeadingFont, "same", "sans", "serif", "mono")
+	t.Font = pick(t.Font, "sans", "serif", "mono", "fira")
+	t.HeadingFont = pick(t.HeadingFont, "same", "sans", "serif", "mono", "fira")
 	t.FontSize = pick(t.FontSize, "normal", "small", "large")
 	t.CustomFont = fileID(t.CustomFont)
 	t.CustomHeadingFont = fileID(t.CustomHeadingFont)
@@ -410,10 +410,16 @@ func fontStack(name string) string {
 		return `Georgia, "Times New Roman", Times, serif`
 	case "mono":
 		return `"Courier New", Courier, monospace`
+	case "fira":
+		return `"Fira Code", "Fira Mono", Menlo, Consolas, "Courier New", monospace`
 	}
 	return `"Helvetica Neue", Helvetica, Arial, sans-serif`
 }
 
+// UsesFira says whether the bundled Fira Code face must be declared: the
+// only built-in choice that is a web font rather than a system stack.
+func (t Theme) UsesFira() bool { return t.Font == "fira" || t.HeadingFont == "fira" }
+
 // Helpers used by the CSS template. The @font-face families are named for
 // their role, so a stack is the uploaded font first and the built-in choice as
 // its fallback.
@@ -516,6 +522,9 @@ func (t Theme) HeaderImageMaxHeight() string {
 }
 
 var themeCSS = template.Must(template.New("theme").Funcs(template.FuncMap{"sub": func(a, b int) int { return a - b }}).Parse(`
+{{- if .UsesFira}}
+@font-face { font-family:"Fira Code"; src:url(/static/FiraCode-VF.woff2) format("woff2"); font-weight:300 700; font-display:swap; }
+{{- end}}
 {{- if .CustomFont}}
 @font-face { font-family:"BlogFont"; src:url(/media/{{.CustomFont}}); font-display:swap; }
 {{- end}}