panel: add spacing option

README.md

@@ -67,6 +67,14 @@ Optional monitor filter:
 
 An empty or missing `output` list leaves Waybar on its default outputs.
 
+Module spacing:
+
+```json
+{
+  "spacing": 10
+}
+```
+
 ## Module Resolution
 
 The config stores logical module names. At generation time, the panel merges

data/config.json

@@ -2,6 +2,7 @@
   "position": "top",
   "type": "panel",
   "output": [],
+  "spacing": 10,
   "modules_left": [
     "image#menu",
     "tray"

src/config.go

@@ -21,6 +21,7 @@ type Config struct {
 	Position      string   `json:"position"`
 	Type          string   `json:"type"`
 	Output        []string `json:"output"`
+	Spacing       int      `json:"spacing"`
 	ModulesLeft   []string `json:"modules_left"`
 	ModulesCenter []string `json:"modules_center"`
 	ModulesRight  []string `json:"modules_right"`
@@ -83,6 +84,10 @@ func (c Config) Validate() error {
 		}
 	}
 
+	if c.Spacing < 0 {
+		return errors.New("spacing cannot be negative")
+	}
+
 	for _, name := range append(append([]string{}, c.ModulesLeft...), append(c.ModulesCenter, c.ModulesRight...)...) {
 		if strings.TrimSpace(name) == "" {
 			return errors.New("module name cannot be empty")

src/generate.go

@@ -14,7 +14,7 @@ func GenerateConfig(cfg Config, registry Registry) ([]byte, error) {
 		"margin-top":             0,
 		"margin-right":           0,
 		"margin-bottom":          0,
-		"spacing":                10,
+		"spacing":                cfg.Spacing,
 		"exclusive":              true,
 		"fixed-center":           true,
 		"reload_style_on_change": true,