Since other users can change their comment pages too, you can either set single pages or all pages to your style.
Single Pages: Add ?style=mine to the end of a comment page's URL to temporarily display that comment page in your style. If the URL already has a ? mark in it, such as ?mode=reply or ?nc=, then add &style=mine instead.
All Pages: Enable the View comment pages from my Friends page in my own style option on the Display tab of the My Account Settings page. This option automatically adds ?style=mine to the URLs of comment pages on your Friends page, so you always see your style on other users' comment pages.
All Journal Pages: Paid and Permanent users can make all journal pages display in their style, including comment pages. To do so, enable the View all journals and communities in my own style option on the Display tab of the My Account Settings page, or click the View in my style link on the Navigation Strip. This option does not add ?style=mine to the URLs of comment pages, so if you want to see a comment page in its original style, you must turn off this option.
Some changes have been made to LiveJournal, and we hope you enjoy them! As we continue to improve the site on a daily basis to make your experience here better and faster, we would greatly appreciate your feedback about these changes. Please let us know what we can do for you!