Port the web to bootstrap5

So it is responsive in phones.

lib/template.go

@@ -23,6 +23,7 @@ var tmpl_funcs = map[string]interface{}{
 	"strings_join": stringsJoin,
 	"download_url": downloadUrl,
 	"size2mb":      size2mb,
+	"mul":          mul,
 }
 
 type Status struct {
@@ -114,6 +115,10 @@ func size2mb(size int) float32 {
 	return float32(size) / (1024.0 * 1024.0)
 }
 
+func mul(a, b int) int {
+	return a * b
+}
+
 type DevTemplateExecutor struct {
 	assetsPath string
 	tpe        string