Subrouter fix

main.go

@@ -9,7 +9,9 @@ import (
 	"github.com/gorilla/mux"
 	"html/template"
 	"net/http"
+	"path"
 	"path/filepath"
+	"strings"
 )
 
 func main() {
@@ -63,7 +65,7 @@ func setupFrontend(r *mux.Router) {
 	landingpage := template.Must(template.ParseFiles(filepath.Join(config.FrontendDir, "html", "landingpage.gohtml")))
 
 	r.PathPrefix("/").HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.URL.Path == "/" {
+		if strings.TrimPrefix(r.URL.Path, path.Dir(config.Prefix)) == "/" {
 			landingpage.Execute(w, config.PageBase)
 		} else {
 			server.Error404(w, r)