title: Angular set css dynamically of :before selector
body: <p>I need to label an upload button dynamically. My code so far:</p>
  
  <pre><code>&lt;style&gt;
     .file_upload_wrap.background_file:before {
      content: {{label}};  /* of course does not work */
    } 
  &lt;/style&gt;
  
  &lt;div class="file_upload_wrap background_file imgFormButton"&gt;
      &lt;input type="file" class="file_upload" (change)="uploadFile($event, file)" name="file" id="file" [(ngModel)]="model.file"
        #file="ngModel"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>How can I set the content dynamically?</p>