tolerance for non-square logo

static/terms-of-service.html

 <h4>Terms of Service</h4>
 
 <p>This is a placeholder ToS. Edit <code>"/static/terms-of-service.html"</code> to make it fit the needs of your instance.</p>
-<img width="50px" height="50px" src="/static/logo.png" style="display: block; margin: auto;" />
+<img src="/static/logo.png" style="display: block; margin: auto; max-width: 100%; height: 50px; object-fit: contain;" />