Knowledge Reserve of CSS
If you do not have knowledge about CSS, please refer to the content in the page CSS Resources section. Before you start to make changes to the Confluence style sheet, you should have some knowledge of the CSS and a repository for it.
Safety
Custom CSS has the potential to inject scripts into the page, with the risk of cross-site attacks Cross-site scripting (XSS). When the custom script upload feature is enabled, the space administrator can upload a CSS stylesheet with his or her username and password, and then trigger the browser to run the script when the page is loaded, which may not even be known to the space administrator, or worse, to gain administrator privileges. Based on this consideration, this feature is disabled by default. Confluence administrators should only enable their familiar CSS files and try to avoid the risk of security by using a CSS file of unknown origin.
Scaling
Each page needs to be scaled. Depending on the browser used by each user, the content of the page should be able to be scaled correctly based on different browsers. The CSS you design should be able to take this into account. Try to perform some scaling tests on the Confluence page, which requires testing many pages of space, such as drafts, labels, page inheritance, and so on. The style sheet you are designing should work properly under all circumstances, not just the first page to work properly.
Features that cannot be disabled
Closing some links, headers, even the entire menu is very easy and you just need to set the stylesheet as ' hidden ' on it. This may help users who are not very good at wikis. A simple UI design can help the user to use it better. Please note that the links you hide do not mean that these features are not present in the system. Users can also reuse or get access to the URLs they use by modifying their browser's style sheets. Don't expect to use CSS to help you disable some of the features of confluence.
Attributes that should not be disabled
The confluence user wants the relevant actions to be displayed in the same place at the same time. Deleting the buttons on the Confluence page or hiding them will prevent users from accessing and using confluence, and these users may bypass your disabling of the buttons through specific URLs.
Custom CSS cannot be applied to the admin interface
The use of any custom CSS at your site will not affect the system Administrator console. This setting is intended to prevent user methods from confluence the console's functionality by customizing the CSS.
Confluence version compatibility
When you plan to upgrade your confluence, you need to be careful. Subsequent versions of Confluence may not be compatible with the custom CSS you are currently using-this may cause your CSS to be corrupted, which will require you to maintain your custom CSS file after upgrading confluence. Please ask your Confluence administrator for more information.
Testing in different browsers
You should test your modified CSS confluence site in a different browser. Internet Explorer, Chrome, Firefox,opera, and Safari (Mac OS X) are the most user-used browsers
CSS customizations are not supported
Creating a custom CSS may lead to a variety of potential possibilities, and Atlassian will not support custom CSS generation or related issues.
Https://www.cwiki.us/display/CONFLUENCEWIKI/Styling+Confluence+with+CSS
Confluence 6 consider using custom CSS