panel: add end margin option

README.md

@@ -75,6 +75,14 @@ Module spacing:
 }
 ```
 
+End margins for floating and island panels:
+
+```json
+{
+  "end_margin": 8
+}
+```
+
 ## Module Resolution
 
 The config stores logical module names. At generation time, the panel merges

data/config.json

@@ -3,6 +3,7 @@
   "type": "panel",
   "output": [],
   "spacing": 10,
+  "end_margin": 8,
   "modules_left": [
     "image#menu",
     "tray"

src/config.go

@@ -22,6 +22,7 @@ type Config struct {
 	Type          string   `json:"type"`
 	Output        []string `json:"output"`
 	Spacing       int      `json:"spacing"`
+	EndMargin     int      `json:"end_margin"`
 	ModulesLeft   []string `json:"modules_left"`
 	ModulesCenter []string `json:"modules_center"`
 	ModulesRight  []string `json:"modules_right"`
@@ -88,6 +89,10 @@ func (c Config) Validate() error {
 		return errors.New("spacing cannot be negative")
 	}
 
+	if c.EndMargin < 0 {
+		return errors.New("end margin 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

@@ -35,7 +35,7 @@ func GenerateConfig(cfg Config, registry Registry) ([]byte, error) {
 	}
 
 	if cfg.Type == "floating" || cfg.Type == "islands" {
-		applyFloatingMargins(out, cfg.Position)
+		applyFloatingMargins(out, cfg.Position, cfg.EndMargin)
 	}
 
 	left, err := resolveModuleList(cfg.ModulesLeft, cfg.Position, registry)
@@ -62,24 +62,26 @@ func GenerateConfig(cfg Config, registry Registry) ([]byte, error) {
 	return append(data, '\n'), nil
 }
 
-func applyFloatingMargins(out map[string]any, position string) {
+func applyFloatingMargins(out map[string]any, position string, endMargin int) {
+	const edgeMargin = 8
+
 	switch position {
 	case "top":
-		out["margin-top"] = 8
-		out["margin-left"] = 8
-		out["margin-right"] = 8
+		out["margin-top"] = edgeMargin
+		out["margin-left"] = endMargin
+		out["margin-right"] = endMargin
 	case "bottom":
-		out["margin-bottom"] = 8
-		out["margin-left"] = 8
-		out["margin-right"] = 8
+		out["margin-bottom"] = edgeMargin
+		out["margin-left"] = endMargin
+		out["margin-right"] = endMargin
 	case "left":
-		out["margin-top"] = 8
-		out["margin-bottom"] = 8
-		out["margin-left"] = 8
+		out["margin-left"] = edgeMargin
+		out["margin-top"] = endMargin
+		out["margin-bottom"] = endMargin
 	case "right":
-		out["margin-top"] = 8
-		out["margin-bottom"] = 8
-		out["margin-right"] = 8
+		out["margin-right"] = edgeMargin
+		out["margin-top"] = endMargin
+		out["margin-bottom"] = endMargin
 	}
 }