docs: add styles section and examples

README.md

@@ -152,6 +152,25 @@ logger.SetReportCaller(false)
 logger.SetLevel(log.DebugLevel)
 ```
 
+### Styles
+
+You can customize the logger styles using [Lipgloss][lipgloss]. The styles are
+defined at a global level in [styles.go](./styles.go).
+
+```go
+// Override the default error level style.
+log.ErrorLevelStyle = lipgloss.NewStyle().
+    SetString("ERROR!!").
+    Padding(0, 1, 0, 1).
+    Background(lipgloss.Color("204")).
+    Foreground(lipgloss.Color("0"))
+// Add a custom style for key `err`
+log.KeyStyles["err"] = lipgloss.NewStyle().Foreground(lipgloss.Color("204"))
+log.Error("Whoops!", "err", "kitchen on fire")
+```
+
+<img width="400" src="https://vhs.charm.sh/vhs-1s1qma0OVFeWFGqtBAPpfW.gif" alt="Made with VHS">
+
 ### Sub-logger
 
 Create sub-loggers with their specific fields.

examples/styles/styles.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"time"
+
+	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/log"
+)
+
+func main() {
+	log.ErrorLevelStyle = lipgloss.NewStyle().
+		SetString("ERROR!!").
+		Padding(0, 1, 0, 1).
+		Background(lipgloss.Color("204")).
+		Foreground(lipgloss.Color("0"))
+	log.KeyStyles["err"] = lipgloss.NewStyle().Foreground(lipgloss.Color("204"))
+	logger := log.New()
+	logger.Error("Whoops!", "err", "kitchen on fire")
+	time.Sleep(3 * time.Second)
+}

examples/styles/styles.tape

@@ -0,0 +1,8 @@
+Output styles.gif
+
+Set Height 250
+Set Width 700
+
+Type "./styles" Sleep 500ms Enter
+
+Sleep 3s