title: Let iOS pick the System Font Helvetica Neue or San Francisco in CSS
body: <p>Is it possible to specify a system font in a <code>CSS</code> targeted to iOS (to be displayed in a <code>UIWebView</code>), and get similar results as when designing with <strong>Interface Builder</strong>:</p>
  
  <p><a href="https://i.stack.imgur.com/1IghB.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1IghB.png" alt="IB Font Menu"></a></p>
  
  <p>Can a <code>CSS</code> set <em>System</em>, <em>System+Weight</em> or <em>Text Styles</em> instead of <code>font-family:Helvetica Neue</code>:</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;style type=\"text/css\"&gt;
      body{font-family:Helvetica Neue; font-size:14;}
  &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;&lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <hr>
  
  <p><strong>System</strong></p>
  
  <pre><code>UIFont.systemFontOfSize(), UIFont.boldSystemFontOfSize(), UIFont.italicSystemFontOfSize()
  </code></pre>
  
  <p><strong>System+Weight</strong></p>
  
  <p>As in <code>let mediumWeight = UIFont.systemFontOfSize(17, weight: UIFontWeightMedium)</code></p>
  
  <pre><code>UIFontWeightUltraLight, UIFontWeightThin, UIFontWeightLight, UIFontWeightRegular, UIFontWeightMedium, UIFontWeightSemibold, UIFontWeightBold, UIFontWeightHeavy, UIFontWeightBlack
  </code></pre>
  
  <p><strong>Text Styles</strong></p>
  
  <pre><code>Body, Callout, Caption 1, Caption 2, Footnote, Headline, Subhead, Title 1, Title 2, Title 3
  </code></pre>