Is there a plugin to modify HTML code of web page?

I've got a website that I use that has a fixed height tag in the HTML code to 500 px instead of auto. This limits the screen to showing only 500px of a table while my screen res is 1200+ px. Is there something that I could say replace XXX with YYY on all pages that contain it on ZZZ domain?

ORIGINAL:

<div class="x-panel-body x-panel-body-noheader" id="ext-gen128" style="height: 500px;">

REPLACE WITH:

<div class="x-panel-body x-panel-body-noheader" id="ext-gen128" style="height: auto;">