"Quickly design and customize responsive mobile-first sites with Bootstrap, the world’s most popular front-end open source toolkit, featuring Sass variables and mixins, responsive grid system, extensive prebuilt components, and powerful JavaScript plugins."https://getbootstrap.com/

In version 13, Tiki moved from a native layout design and CSS to the Bootstrap framework, which provides many benefits including visual consistency throughout the many Tiki features, easier theming, responsive design for compliance with all standard PC and mobile device displays, along with greater workflow familiarity for designers and HTML integrators.

Pre-Bootstrap native layout and CSS Until Tiki12
Bootstrap 3 Updating a pre-Bootstrap theme Tiki13 to Tiki18 LTS
Bootstrap 4 Updating a Tiki theme from Bootstrap 3 to 4 Tiki19 to Tiki24 LTS
Bootstrap 5 Tiki25+

When Bootstrap 6 is released, the Tiki community will migrate to it after an LTS version, so as to minimize disruption within an LTS cycle. See Versions.

See also: https://blog.getbootstrap.com/2021/08/19/ten/

See also Mobile