title: Input type='file' accept pdf and excel file extension
body: <p>I want an input <code>type="file"</code> to accept only pdf and excel</p>
  
  <p>I did this <code>&lt;input type="file" name="upload" accept="application/pdf,application/vnd.ms-excel" /&gt;</code></p>
  
  <p>And it accepts .pdf and .xls files, but not .xlsx, how can I make it accept xlsx files as well?</p>