try this, I used the tag <center> </center>, I'm not sure about backward compatibility, but I tested in Chrome and Mozilla Firefox, and there are current ones.
code example (does not need CSS):
<div class="progress progress-striped active" style="margin:0 10%;display:none;" id="uploadProgressbar">
<center><b><span class="progress-value" id="uploadProgressValue" style="color:red;">00%</span> </b></center>
<div class="progress-bar progress-bar-primary" role="progressbar" id="uploadProgress" aria-valuenow="40" aria-valuemin="0" aria-valuemax="100" style="width: 0%">
</div>
</div>
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