I've exhaustively attempted various CSS strategies within the embed, but have been unsuccessful in expanding its width beyond 500px.
<a class="twitter-timeline" data-widget-id="694535126655635456" href="https://twitter.com/TwitterDev" width="1300" height="750">Tweets by @PTDcommish</a>
<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+"://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");</script>
Here are some of the CSS tweaks I've experimented with:
#twitter-widget-0 {
width: 100% !important;
}
.twitter-timeline-rendered {
width: 100% !important;
}
iframe[id^='twitter-widget-']{
width:100%;
}
.twitter-timeline {
width: 100% !important;
}