golang present tool show line numbers?

output

$ go get -u code.google.com/p/go.tools/cmd/present
$ present -orighost=localhost
2014/10/03 09:49:52 Open your web browser and visit http://localhost:3999
2014/10/03 09:49:57 accepting connection from: 127.0.0.1:50701

x.go

package main

import (
	"fmt"
)

func main() {
	fmt.Println("hello")
}

x.slide

Title
Sub-title
7 Oct 2014

Marty Schoch
[email protected]

* Show code with line numbers
.code -numbers x.go

I worked around this by modifying styles.css to include:

.numbers span:before {
  content: attr(num);
  color: gray;
  display: block;
  float: left;
  width: 2em;
}