title: Change value of a class variable with one click? (simplest way)
body: <p>I'm looking for a way to easily change one of variable's value. There's a chat in a browser game that I want to make taller. Changing height in dev tools does the work:</p>
  
  <pre><code>&lt;div class="tsbchat" style="position: relative; width: 100%; height: 160px; margin-bottom: 20px;"&gt;
  </code></pre>
  
  <p>But can I make i.e. a script and put it in bookmarks that will allow me to change this value with one click? How would it look like? I know it's a trivial question but I'm a noob, you can remove the question and I will find help somewhere else. Thanks in advance!</p>