Index36 - is a Modern Responsive Theme for Cotonti Siena built with Bootstrap 5.3. Build different kinds of CMS from a simple business card site to a full social network.  

The theme is perfect for projects ranging from simple business cards to complex portals, including blogs, marketplaces, freelance platforms, forums, and corporate websites. Index36 is a full-featured ecosystem for website users. The main focus is on the sidebar, which serves as the central hub for navigation and administration. 

The website template is simple enough for a quick start and immediate customization. Suitable for beginner to advanced developers. Not for complete novices!

The release has taken place! 24.02.2026. Demo site.

I am not attaching the archive file because the latest version of the code is always available for free in the GitHub repository.

The link is at the end of the description.

Index36: Modern Theme for Cotonti CMF – Flexibility, Style, and Convenience

Introduction to Index36

Index36 is an innovative theme for Cotonti Siena, one of the most flexible and powerful PHP-based CMFs. Designed with modern web design trends in mind, this theme combines an elegant interface, high performance, and extensive customization options. Created by web development enthusiast under the pseudonym webitproff, Index36 is aimed at users seeking a professional-looking site without compromising functionality. The theme is ideal for projects from simple business cards to complex portals, including blogs, forums, and corporate websites.

With a focus on both administrators and end-users, Index36 integrates advanced content management tools, providing a seamless experience across all devices. Thanks to its open BSD license, the theme is available for free use and distribution while preserving copyright, making it attractive to the Cotonti developer community.

Key Design Features

Index36 stands out with a minimalist yet expressive design inspired by modern web standards. The theme uses responsive layouts that automatically adapt to smartphones, tablets, and desktops, ensuring optimal content display under any conditions.

• Dark and Light Mode Support: Users can switch between light and dark themes with a single click, considering the browser's system preferences. This not only improves readability at different times of day but also reduces eye strain, making site interaction more comfortable.
• Integration of Modern Libraries: Built-in Bootstrap support provides responsive elements such as modals, notifications, and navigation panels. Font Awesome adds a rich set of icons for visual accents, while Perfect Scrollbar ensures smooth scrolling in sidebars, even with large amounts of content.
• Customizable Header and Footer: The site header includes a logo, sidebar toggle, language selector, notifications, and user profile. The footer displays technical information such as PHP version, compatibility mode, and page generation statistics, which is useful for administrators.

The design emphasizes clean lines and a focus on content, using color variables for easy CSS customization.

Functionality and User Interface

Index36 is not just a template – it is a full-featured ecosystem for website management. The main focus is on the sidebar, which serves as the central hub for navigation and administration.

• Expandable Tabbed Sidebar: The sidebar is divided into thematic tabs, including pages (articles and news), forums, users, plugins, and additional elements. Each tab opens a panel with quick access to search, categories, and administrative tools. On mobile devices, the sidebar collapses to save space but remains accessible with a click.
• Localization and Frontpage Content: The theme includes complete Russian localization with custom interface strings. The homepage features sections for beginners, such as "What is Cotonti?", explaining the advantages of the CMF. Additional blocks cover app downloads, development services (plugins, modules, templates), and migration from other CMSs like WordPress or Bitrix.
• Administrative Tools: Administrators have quick links for page moderation, module configuration (Pages, Forums, Users), managing extrafields, and group permissions. This simplifies daily tasks such as editing categories, forum search, or statistics analysis.
• Module and Plugin Integration: The theme seamlessly integrates with popular Cotonti modules such as forums, users, and pages. Plugin support, like whosonline, statistics, and contact, adds functionality including online user display, analytics, and feedback forms.

The user experience is enhanced with elements such as new message notifications, profile avatars, and content file insertion tools.

Compatibility and Installation

Index36 is fully compatible with Cotonti Siena version 0.9.26 and higher, running on PHP 8.4 and MySQL 8.0. The theme uses built-in Cotonti resources for library inclusion, minimizing dependencies and ensuring fast load times.

• Requirements: The theme does NOT support legacy mode for compatibility with old tags. If you are building a new website, there is nothing to worry about. If your engine version is outdated, it is long overdue for an upgrade.
• Installation: Installation guide for the “Index36” theme.

The developer provides support through the community forum and GitHub, including free consultations and paid enhancements.

Conclusion

Index36 is not just a theme, but a tool for creating professional Cotonti websites. Combining aesthetics, functionality, and simplicity, it is ideal for developers who want to quickly deploy a project and administrators who value convenience. With open-source code and an active community, Index36 continues to evolve, offering endless personalization possibilities. If you are looking for a balance between style and efficiency, this theme will provide a reliable foundation for your next web project.

Permanent link to the latest source code on GitHub.