title: Adding a CSS file with custom font (font-face)
body: <p>I try to include a CSS file with custom font (via using @font-face)</p>
  
  <p><strong>Lib/main.js :</strong></p>
  
  <pre><code>var pageMod = require("sdk/page-mod");
  var self = require("sdk/self");
  pageMod.PageMod({
    include: "*",
    contentStyleFile: [self.data.url("css/fontello/fontello.css")]
  });
  </code></pre>
  
  <p><em>(This work correctly, tested by adding background-color)</em></p>
  
  <p>But I think I have problem to local <strong>font path</strong>..</p>
  
  <p><strong>This is my folder look like</strong></p>
  
  <p><img src="https://i.stack.imgur.com/pjXJT.png" alt="enter image description here"></p>
  
  <p>And my <strong>fontello.css</strong> with @font-face look like.. <em>(This is just a part of fontello)</em></p>
  
  <pre><code>@font-face {
    font-family: 'fontello';
    src: url('fontello.eot?25255831');
    src: url('fontello.eot?25255831#iefix') format('embedded-opentype'),
         url('fontello.woff?25255831') format('woff'),
         url('fontello.ttf?25255831') format('truetype'),
         url('fontello.svg?25255831#fontello') format('svg');
    font-weight: normal;
    font-style: normal;
  }
  </code></pre>
  
  <p>After this , I try to add a element with my custom font, It doesnt work</p>
  
  <p><strong>What is this src sholud be ?</strong></p>
  
  <hr>
  
  <p>Tested :</p>
  
  <pre><code>data/css/fontello/fontello.{font-ex}
  /data/css/fontello/fontello.{font-ex}
  css/fontello/fontello.{font-ex}
  /css/fontello/fontello.{font-ex}
  fontello/fontello.{font-ex}
  /fontello/fontello.{font-ex}
  fontello.{font-ex}
  /fontello.{font-ex}
  </code></pre>
  
  <p>Noone works :(</p>