diff --git a/config.go b/config.go
index a284137..a081177 100644
--- a/config.go
+++ b/config.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/eeeXun/gtt/internal/style"
 	"github.com/eeeXun/gtt/internal/translate"
 	config "github.com/spf13/viper"
 )
@@ -15,7 +16,7 @@ func configInit() {
 		defaultConfig     = map[string]interface{}{
 			"hide_below":                             false,
 			"transparent":                            false,
-			"theme":                                  "Gruvbox",
+			"theme":                                  "gruvbox",
 			"source.border_color":                    "red",
 			"destination.border_color":               "blue",
 			"source.language.apertiumtranslate":      "English",
@@ -42,7 +43,7 @@ func configInit() {
 	}
 	config.AddConfigPath("$HOME/.config/gtt")
 
-	// Create config file if not exists
+	// Create config file if it does not exist
 	// Otherwise check if config value is missing
 	if err := config.ReadInConfig(); err != nil {
 		for key, value := range defaultConfig {
@@ -60,6 +61,11 @@ func configInit() {
 				missing = true
 			}
 		}
+		// Set to default theme if theme in config does not exist
+		if IndexOf(config.GetString("theme"), style.AllTheme) < 0 {
+			config.Set("theme", defaultConfig["theme"])
+			missing = true
+		}
 		if missing {
 			config.WriteConfig()
 		}
diff --git a/internal/style/color.go b/internal/style/color.go
index a90eca4..29069c4 100644
--- a/internal/style/color.go
+++ b/internal/style/color.go
@@ -5,10 +5,10 @@ import (
 )
 
 var (
-	AllTheme = []string{"Gruvbox", "Nord"}
+	AllTheme = []string{"gruvbox", "nord"}
 	Palette  = []string{"red", "green", "yellow", "blue", "purple", "cyan", "orange"}
 	themes   = map[string]map[string]tcell.Color{
-		"Gruvbox": {
+		"gruvbox": {
 			"bg":     tcell.NewHexColor(0x282828),
 			"fg":     tcell.NewHexColor(0xebdbb2),
 			"gray":   tcell.NewHexColor(0x665c54),
@@ -20,7 +20,7 @@ var (
 			"cyan":   tcell.NewHexColor(0x8ec07c),
 			"orange": tcell.NewHexColor(0xfe8019),
 		},
-		"Nord": {
+		"nord": {
 			"bg":     tcell.NewHexColor(0x3b4252),
 			"fg":     tcell.NewHexColor(0xeceff4),
 			"gray":   tcell.NewHexColor(0x4c566a),