This Chrome, Firefox, Opera and IE user style sheet replaces the ugly Comic Sans MS font on all websites with much better Comic Neue font by Craig Rozynski. This web font is hosted on the super-fast CDN jsDelivr.
For Chrome, install the extension from the Chrome Web Store and voilà!
For Stylish, install the user style from userstyles.org.
For other browsers, first download just the userContent.css file.
In Firefox, go to about:support and click Open Directory of your profile. Create a new folder chrome and paste the userContent.css file into it.
In Opera, click View > Style > Manage Modes and choose the userContent.css file.
In Internet Explorer, click Internet Options > Accessibility > Format documents using my stylesheet and browse for the userContent.css file.
Comic Neue font by Craig Rozynski in the Public Domain.
Comic Sans Replacer by Jerzy Głowacki under Apache 2.0 License.