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Blueprint: CSS-Unification

Proposal Provide guidelines for having the same CSS classes for common uses throughout the TYPO3 CMS Backend, and a plan on how to introduce newly namespaced CSS classes
Owner/Starter Benni Mack
Participants/Members -
Status Draft, Discussion, Voting Phase, Accepted, Declined, Withdrawn
Current Progress Unknown, Started, Good Progress, Bad Progress, Stalled, Review Needed
Topic for Gerrit CSS

Target Versions/Milestones

Started during TYPO3 CMS 6.2+ development

Goals / Motivation

The idea is to unify the HTML output and styling information within the TYPO3 backend. This makes it easy in the future to easily modify the TYPO3 Backend in a clean and straightforward way.


There are certain ground rules that need to be followed by each CSS directive:

1) Distinguish between CSS classes used for styling, CSS classes for JS selections, and information about a record.

  • As IDs are only allowed once per page, and with a dynamic page one never knows if an ID is already in use, that's why the TYPO3 Backend prohibits IDs for CSS information.
  • Only use CSS classes where needed, rather use proper HTML5 elements to define certain parts of a page (<header> / <footer> and not
    ) and proper cascading for CSS classes
  • IDs and CSS classes need to be distinguishable where they are used, either for JS use, CSS use. Don't combine them in one.
  • All CSS classes are written in lowercase, all data attributes as well

2) Use a common namespace for CSS names

  • t3- for all styling-related HTML elements
  • t3js- for all javascript-related DOM elements - no styling is allowed to be referenced to these classes

As the TYPO3 Backend incorporates many other frameworks (maybe via extensions), it is clearly defined whether a CSS class is introduced and used by TYPO3 or not.

3) Explain the object, not the functionality or the information that will be attached to it

Example: A default table (that actually displays tabular data)





Example: An information box that shows a warning


 class="t3-messagebox t3-yellowbackground"


 class="t3-message t3-warning"

4) Only use CSS classes where applicable




<h4 class="t3-uppercase">...</h4>

5) Use multiple classes to define more concrete implementations

Usually, an HTML element has a base CSS class, then can be defined what additional features / information the HTML element holds.

6) Use hyphens as seperation between generic CSS classes and their more specific counterparts

 <form class"t3-form t3-form-filterable">

7) Use data attributes to store information, never use CSS classes for that

 <form class"t3-form t3-form-filterable t3js-dataform" data-table="tt_content" data-uid="123">

Implementation Details

  • It needs to be decided whether to use SASS or LESS in order to have more consistent code.
  • Also, a guideline needs to be shown what available classes are there in order to use them properly.
  • Currently, the backend CSS is split into structure and visual. As this separation does not make a lot of sense now.
  • Define good standards for common use cases (see and identify all screens of the Backend, PDF made by the usability team)

Also see


Breaking of Extensions that ship with a backend module that use current CSS classes of the TYPO3 Backend.

Issues and reviews

Dependencies upon other Blueprints

External links for clarification of technologies