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                <h1>Using The Default Operating System Font in CSS</h1>

<li>On Ubuntu this should be the Ubuntu Font.</li> 
<li>On Yosemite this should be Helvetica Neue.</li>
<li>On El Capitan this should be San Francisco.</li>
<li>On Windows XP this should be Tahoma.</li>
<li>On newer Windows this should be Segoe UI.</li>
<li>On Windows Phone this should be Segoe UI.</li>
<li>On Android this should be Roboto.</li>
<li>On iOS9 this should be San Francisco.</li>
<li>On iOS8 this should be Helvetica Neue.</li>
<li>On Blackberry OS this should be in BBAlphaSans.</li>

<small><strong>Notes:</strong> Unfortunately “font: caption” breaks on iOS (sets the font-family always to “Times”), thus we need to use JavaScript to detect it. On other operating systems everything is working just fine. On Windows XP, the system font is used in Internet Explorer, but other browsers display the content using Arial.</small>

<small><strong>Tested in:</strong> Safari 9 on El Capitan, Chrome 46 on El Capitan, Firefox 41 on El Capitan, Opera 32 on El Capitan, MS Edge on Windows 10, Internet Explorer 8 on Windows XP, Chrome 46 on Windows XP, Firefox 41 on Windows XP, Internet Explorer 9 on Windows Phone 7.5, Chrome Mobile on Android 6.0, Firefox Mobile on Android 6.0, Dolphin Mobile on Android 6.0, Samsung Stock WebKit on Android 4.4, Safari on iOS8, Safari on iOS9, Blackberry browser on BB OS 7.</small>



                body {
  // Used as a fallback:
  font-family: sans-serif;
  // Set everything to use the system font:
  font: caption;
  font-weight: 400;
  font-size: 100%;
  max-width: 400px;
  margin: 2rem;
  // Unfortunately “font: caption” breaks completely on iOS, thus:
  .ios & { font-family: "-apple-system", "HelveticaNeue", sans-serif }

h1 {
  font-size: 150%;
  font-weight: 700;
  margin: 0 0 .6em;

small {
  font-size: 75%;
  margin: 2em 0 0;
  display: block;

strong {
  font-weight: 700;


                // Microsoft injected the word “iPhone” in IE11’s userAgent, which is why I’ve added the !window.MSStream here:
if (navigator.userAgent.match(/(ipad|iphone|ipod)/i) && !window.MSStream) {
  document.documentElement.className += " ios";