发布 KALLYAS - Responsive Multi-Purpose WordPress Theme 4.1.3


KALLYAS – the all-in-1 multipurpose WordPress theme. Responsive, lightweight, drag & drop visual page builders & no coding required. 6 months support included.
We found Kallyas in so many professional businesses, it’s incredible how creative people are. This clean & modern Theme can be used as a one page website, blog, photography portfolio or gallery, corporate, agency, real estate, hotel, furniture shop, travel, medical (healthcare), education, fitness, retail, fashion & beauty, landing page, app, admin, jewelry, food & restaurant, interior church nonprofit. eCommerce – WooCommerce available. Retina & RTL ready. Parallax & Revolution slider. Awesome support community.
With over 17,000 satisfied customers, the applications for Kallyas are almost endless. With our super easy to use drag and drop page builder “Visual Builder”, developed right out of the box (no plugins required) you can build almost any page imaginable. It’s as simple as 1, 2, 3. Really!
1. Drag and Drop your element
2. Edit your element (image, video, whatever!)
3. Select your settings, Save & Close.
Huzzah! Instantly beautiful pages on the fly. No coding required. We promise.
Not only that, but we have included over 100 pre-built elements to suit any application – and with a powerful Live Search feature built in too, there won’t be any wasted time fumbling around looking for these elements either.
Our powerful workflow tools remove the need for additional Photoshop designers with the ability to design on the go, without the need for any coding, and every element is reusable.
Save your entire page as one design template and reuse it over and over for seamless, beautiful pages every time.
As a Kallyas customer you will have full access to our Video Documentation database, our existing customers LOVE this service making it easy to find detailed video descriptions for all elements of building websites with Kallyas.
Still not satisfied? What about Live Chat with our incredibly dedicated Support Team? Yup, not only do we have a complete Video database ready to roll, as well as detailed written documentation, we have Live Chat for those urgent questions.
You can believe us when we say that Kallyas really is a Gigantic WordPress Toolbox for building beautiful websites.

Creating a website is easier than ever. All this with our custom
built page builder and Kallyas, which is built around it.
It can make your work much more enjoyable and also time-saving!

Currently we’re housing 12 unique combined homepages for lots of different purposes. Among them, we also remade the classic homepages which were crazy gorgeous and useful.
Bear with us as we’re going to continuously add more homepages and custom pages. Any feedback is more than welcome, so if you have suggestions, please do share them!
Browse Homepages

Kallyas is ready as an eCommerce platform, having built-in styles for WooCommerce plugin, which at this moment empoweres ~30% of the world online stores!!
Currently inside Kallyas, we added 3 different store landing pages and refreshed the overall feel and layout, but we’re planning to continuously release new niched demos and entirely new styles.
- Periodically try dropping a visit, you’re more than welcome!
Browse Shop Features

There’s a huge variety of top page sliders, slideshows and hero scenes. Each one is more beautiful than the other.
They really look fantastic and we recommend browsing each one, while enjoying a tea or a coffee

Browse Sliders and Hero Scenes

Make your website as unique as possible, with almost endless combinations. It’s almost like productive gaming!

Safely update your WordPress instance as we’re one step ahead to ensure Kallyas is running smooth with the latest WordPress releases.

Kallyas has its core based on the sleek, intuitive, and powerful front-end framework for faster and easier web development.

You be the creative, while we’re going to ensure a proper infrastructure for your website, all live in the frontend of your website. Building a website has never been so easy and comfortable.


Web is evolving and portable devices are the fastest growing market of the last decade. So, from smartphones to tablets and desktop computers, your website will be accessible and properly optimised for your user’s best visiting experience.

Unlike other WordPress frameworks and page builders, Kallyas is doing its best to load only the necessary resources that you page needs. This will make your website super fast.

Don’t let your website be buried in the other million results. Kallyas has an excellent SEO infrastructure, it’s highly customisable for even better SEO management and it works flawlessly with the popular Yoast SEO plugin.

Kallyas is ready to be translated in any language possible. We payed fine attention to code detailes and left room for a great integration with WPML.

Translation ready? Check! RTL / Arabic language ready? Check! You can easily translate any Kallyas built-in text string with WordPress plugins or even a desktop app.


Add a touch of personality with a special flavour. Colors can be easily changed predominantly but also specifically where you want.

WooCommerce is currently the most popular online shopping platform and Kallyas is strongly integrated with it including its sleek and gorgeous built-in styles. So, while Kallyas handles the visuals, WooCommerce, with it’s enormous plugin library, will cover almost any existing eCommerce functionality.

With just one click only, you can replicate any of our available demos and enhance the development process.

Spoile and land your visitors on custom-uniquely combined homepages, designed to showcase your business’s best of itself. There are literally, endless possibilities.

Stay in touch and always deliver the best content to your loyal visitors with MailChimp, the most powerful mailing platform/software available.

Among many reasons, what makes Kallyas so special is the large number of built-in features and integrations, along premium powerful plugins.

With over 12 already built homepage designs, this is just a glimpse of the actual power and potential of Kallays theme’s features and core page builder.

We believe that the “above the fold” area of your homepage or inner pages should be spectacular! That’s why we have included tens of built-in solutions and choices, among premium licensed slider plugins.

Again, we love “above the fold” areas! They should be spectacular and they should be as actionable as possible to convert any potential visitor to a loyal customer or subscriber.

A wise marketer said “Before doing what your company does, first, you have to be a media company”. Content marketing is the current “thing” and should be treated as such. Blog about the latest news and updates of your company, simple stories stories or entertaining content for your visitors and subscribers.

Your projects deserves the best showcase. Kallyas includes several highly customisable portfolio layouts for your business’s projects, so that your website visitors will actually see the amazing work you’re doing.

With Kallyas’s “pricing tables” element you can easily showcase your services with their specific prices and features, on the fly, with personality and customisability options.

With Kallyas’s “pricing tables” element you can easily showcase your services with their specific prices and features, on the fly, with personality and customisability options.

What’s a holiday without its magic?! Excite your visitors and bond with them, with custom designed subheaders that’ll surely add some smiles.

Revolution Slider is The most Powerfull slider in the World! With a Visual Slider Building Mode you can build and animate your sliders faster than ever.

Email is still the king of online communication and with Kallyas’s built-in Contact form builder, your potential customers can reach you easily and faster than ever. Surveys? Sure! Modal forms? Easy! Just a few clicks and your forms are ready for getting submitted.

Built-in Modal window system with auto triggering & multiple window types (iframe, inline content).

Kallyas theme, at its core, has a compliant, modern and future proof HTML5 markup and CSS3 styling.

Want to get a bit artsy first? Just download the project’s source PSD and start designing. More PSD’s are coming, so stay tuned!

Add an extra sense of curiosity while still being connected with your audience. All by simply hiding your actual website’s content until your development process is finished and launch with whistles and bells.

Connect people and start creating communities with these powerful WordPress tools that are seamlessly integrated into Kallyas theme.

Kallyas has the best icon integration on the market. Simply upload your web font .zip from Fontello , Font Awesome or any other font-icon generator and you are ready to go in seconds.

With Kallyas theme you should never worry about browser accessibility issues, as in any scenario, the website will look and behave identic

One page + parallax
Kallyas offers you the ability to create awesome One Page websites with stuning 3D Parallax effects.

Want our recipe for speed? Kallyas theme + WP Super Cache & Autoptimize plugins will make your website blazing fast and will score the highest grades.

Each Kallyas feature is backed out with a video.

Whether you’re an expert or a beginner, our Support Team will do its best to provide the best possible and helpful answer for the issues that you’re having.

And many, many more !!

We could go on for days, but the fact is – simply put – Kallyas combines both power and good looks. Toghether they make a great product.
Try to visit the demo and get convinced!
Please remember, support is given through our Support Forums.
Full list of Features:

  • WordPress 4.5+ compatible
  • Bootstrap 3 Framework
  • Amazing frontend LIVE Page Builder containing over 100 elements
  • One-Click Data Install
  • Responsive layout
  • Smart Loader
  • SEO Ready
  • WPML Ready
  • Translation ready
  • Unlimited Sub-Headers
  • Unlimited Colors
  • WooCommerce Integration
  • DummyData Included
  • Unlimited Homepage variations
  • Functional NEWSLETTER – MailChimp integration and adaptation
  • Lots of different Kallyas premium features and plugins
  • Huge variety of sliders (also premium licensed ones):
    • iOS Slider
    • Creative Slider (based on Revolution Slider)
    • Shop Sliders (based on Revolution Slider)
    • Fixed Sliders
      • Style 1 (Simple Slider)
      • Style 2 (Nivo Slider)
      • Style 3 (Wow Slider)
    • 3D Cute Slider
    • Fancy Slider
    • Circular Content & Circular Catalogue carousels
    • Static Content / Hero Scenes (huge variety)
    • Portfolio Slider Frames
    • Laptop Slider, multiple styles
    • iCarousel
    • CSS3 Panels
  • 3 Portfolio Layouts
    • Category Layout
    • Sortable Layout
    • Carousels Layout
  • Custom pages designs:
    • FAQ
    • Process
    • Contact us
    • Offline / Coming soon
    • Historic / Timeline
    • Testimonials
    • Team
    • Portfolio Item
    • Blog Item
    • Product page
    • Services
    • Careers
  • Pricing tables
  • Photo Gallery
  • Bonus – Holiday page headers
  • Animated Header
  • Dynamic PHP Contact form
  • Built-in Modal window system with auto triggering & multiple window types (iframe, inline content)
  • HTML5 & CSS3 Ready
  • PSD Files included
  • Great social media support!
  • Lots of Built in styles
  • Good Documentation
  • & many others!!
Many thanks to:

  • Portfolio images: Gleb Kuznetsov
  • Portfolio images: Yoga Perdana
  • General demo images: PixaBay, Unsplash, PicJumbo, UIFaces, GraphicBurger, CreativeBooster (Logos)
  • General demo videos: Coverr, Giraysait (VideoHive)
  • Icons: IcoMoon
  • Scripts & Plugins: WooCommerce, Bootstrap Library, Nivo Slider, Modernizr, Magnific Popup, CarouFredSel, Jquery Countdown, Respond.js, Jquery Flickr, Jquery Easing, Raphael Diagram, Simple weather JS, ScrollMe

Update History

Note: After updating, please clear the browser’s cache or hard reload the page ( for Win Ctrl+F5 or CMD+Shift+R on Macs), or simply try accessing the page with another browser that hasn’t yet cached the website.
UPDATE 4.1.3 / 26 Apr. 2016

Fixed fatal error on older PHP versions (causing issues when accessing Admin)

UPDATE 4.1.2 / 25 Apr. 2016

Improved Theme-Addons manager to work better with multisites
Added Kallyas Child-theme to Theme-Addons manager
Added credentials check for theme registration
Improvement - Allow "Edit with page builder" button only to users with valid permissions

UPDATE 4.1.1 / 25 Apr. 2016

Added new Theme Addons management system and removed TGM
Added custom new custom text field for Historic element
Added progress to Page builder template upload
Added Revolution Slider import during sample data install
Added back "hide desc" option in WooCommerce
Added Contact form element - Timepicker format from WordPress options
Added Contact form element - Datepicker language options
Added z-index utility classes
Added autoplay, loop & vposter to Media container embed video
Added partial fix for Websafe fonts on Mobiles
Added extra list styles
Added Sticky header option for Page Layouts
Updated Revolution Slider to latest version
Fixes PHP notice when the $attachment_url was provided as an array and not string
Fixed Actionbox text color on dark
Fixed Topnav colors
Fixed Cute slider issues
Fixed rich snippets breadcrumbs for shop
Fixed iosslider link wrapping img. (causing image to be hidden)
Fixed sticky header + logo-contain
Fixed WooCommerce columns not displaying properly on small screens
Fixed diagram issues and added new option to change distance between circles
Fixed small lint errors
Fixed small error "headers already sent.."
Fixes for Dark styles
Tweaked "file_frame" in Page builder.

MAJOR UPDATE 4.1 / 18 Apr. 2016

ADDED (Major features):
- Added new demo - ARES. An eCommerce oriented bundle of clean modern and classic design.
- Added Page Builder Smart Areas. You can now Load, append or prepend a Page builder section with content, either on single / multiple pages or globally into the entire website, with only few clicks; Create custom Footers; Create custom Subheaders; Add Page builder content into the “Hidden panel” above the site header.
- Added new Page Layouts system. You can now override a page's layout by overriding options from Kallyas options.
- Implemented new Template Export and Import system. Portability FTW!
- Added Widgets to Page builder. Now they can be added everywhere in the page.
- Added new SHOP Layout - "Modern" which contains new product archive/listings layout, product page layouts, general WooCommerce pages layout;
- Added new BLOG Layout - "Modern";
- Added new style for "Added to cart" confirmation popup functionality
- Added Header style 10 - minimal, spaced and clean design
- Added Header style 11 - centerd Logo between Main menu navigation
- Added Post Formats for Blog posts
- Added - "Hide PB. element on devices" option (viewport breakpoint width)
- Added - Hide PB. element option when logged-in/guest user
- Added - Animation entry on scroll options for PB. elements
- Added custom container width option. Stretch the website as much as you want to.
- Added Skill Bars element

ADDED (Smaller but awesome new features):
- Added Page Builder data to Post Revisions (max. 5)
- Added new style for Cart component in site-header
- Added new styles for Search component in site-header
- Added new styles for Language selector component in site-header
- Added new styles and options for Main navigation
- Added new styles and options for Default SubHeader in General options
- Added new breadcrumbs style in Subheader
- Added header search style selector
- Added button style option in contact form
- Added support for Portfolio Sortable to act as gallery, by opening images as gallery only (not linking to portfolio page)
- Added custom fonts upload mimes
- Added font-weight definition in custom fonts
- Added option to show excerpt in Latest posts 4 (default) element
- Added multiple layouts for Photo Gallery element (simple, slideshow with thumbs, photo album)
- Added image box title font settings
- Added Button element custom color option
- Added custom height option for Image Box element
- Extended custom theme rebranding support
- Added Custom container width option for Sections
- Added options to hide specific header components on mobile
- Added option to have different logo on mobile
- Added "action box" layout to Smart container element
- Added advanced page preloader options and animations
- Added Plain text field for Contact form
- Added "sold-out" badge for WC products
- Added new "Save / Save & Close" UI improvements for element options panels
- Added Live saving for templates and elements
- Added "Support panel" posibility as triggable from main menu
- Added integration with PostLove plugin
- Added 5 & 6 cols for Portfolio Sortable and Portfolio categories
- Added Android Chrome topbar color
- Added option to open single blog images with modal popup
- Added show images option to Latest posts 3 element
- Added Height and 2 / 4 items for Circular content carousel elements
- Added Google maps element Api Key optional field
- Added custom tag option for subtitle in Title Element
- Added option for bottom margin in Image Box element
- Added option for date format
- Added filter for heading tag in Blog archive
- Added text options for Button element
- Added alignment options for Custom menu element
- Added filter to override logo heading tag
- Added blog description to post archives
- Added date picker field to contact form
- Added centered icon for Separator element
- Added advanced header height options
- Added Portfolio Carousels columns option
- Added multi-columns styling for Search Results page
- Added font-size & font-family lists to WP Editor
- Added functionality for clear all elements in the page
- Added keywords for pagebuilder elements. Sections can also be searched by "row, block, container" or Title Element can be searched as "Headline, Heading".
- Updated Revolution slider to

- General improvements and code cleanup
- Improvements for Page builder - Ctrl+S / Cmd+S for PUBLISH
- General improvements for Blog layouts (codebase, options, etc.)
- Improved theme and element options, displaying images/pictograms
- Improved SEO with Alt & Title attributes to Image tags
- Allow product categories to be selected in WooCommerce archive element
- Allow plugins to extend/override theme's page builder elements
- Improved Subheader overidability and customisation
- Improved Deleting an element takes that was taking too long
- Tweak for font-family in dynamic css to wrap in quotes
- Improved sidebar grid positioning
- Grid photo gallery element improvements
- Optimized Blog default archive post image code
- Optimized blog date across layouts/styles
- Allow days from the Weather Box to be translated
- Optimized some slow queries
- Added recommended sizes in image-option fields description
- Improved compatibility with YITH WooCommerce Zoom Magnifier plugin
- Improved compatibility with Contact Form 7 plugin
- Improved Bottom Masks, moved markup to components for easy overidability
- Title element improvements, added letter spacing option
- Added background color fill for bottom masks
- Improved compatibility with both newer and older PHP versions
- General improvements for Media Container element
- Improvements and new options for Newsletter Box element
- Improvements and new options & styles for Social media group element
- Added options to override single page titles for posts and products
- All widgets can now be overridden by child theme
- Escape key support while element dragging
- Added PHP version to Kallyas Dashboard
- Contact form "send me a copy" checkbox
- Added Visual editor pentru Step Box 3 element
- Added transparent state while dragging options panels
- Allow clients to set the reply address manually in Contact Form element
- Added poster option for Iosslider embed iframe
- Added poster option for Section bg embed iframe
- Added poster option & embed iframe for Subheader Element
- Extend Shop Product Presentation element to include extra filters
- Grid photo gallery improvements (cover fit, alt attribute, gutter size)
- Color contrast tweaks
- Improved Header search form to WP standards
- Added stroke option for Iconbox element
- Prettified and restructured header styles codebase for better overidability
- Added image width option for sortable portfolio images
- Added image width option for grid photo gallery
- Confirm modals dirrectly with enter key
- Changed "back" selectors for responsive menu to allow child themes to extend it by adding a "close all" button
- Added WooCommerce plugin to theme addons
- Added swipe for screenshotbox carousel
- Improved parallax scrolling

- General fixes and improvements for performance, enancement and display;
- Small fix to section's close button in modal mode
- Fixed title attribute for modal dynamic window (link target type)
- Fixes for chaser menu bugs (appearing over WP admin bar's dropdowns, appearing in IE)
- Fixed extra closing div in Laptop slider (causing issues with the Page builder)
- Fixed PHP notices related to caching
- Fixed Posts Search (make the text inside page builder elements searchable)
- Fixed page title and subtitle display
- Fixed Portfolio Sortable's Load more button problem with bigger images
- Fixed Showroom carousels height issue
- iOS Slider no fields for Embed videos
- Photo Gallery - Loop between multiple elements
- Blog post multiple columns issues
- Fixed missing "configure red notice" for image box element
- Fix Flickrfeed https warnings
- Fixed linked button in box-model field
- Embed shortcode in Textbox element
- Fixed problems with Grouped products
- Vertical tab not moving content fixes
- Fixed error "cannot modify headers" in ShopProductsPresentation element
- Fixes for Mailchimp widget
- Fixed bug with Youtube Video background
- Fixed iCarousel width/height cropping for custom sizes
- Fixes for Header problems with empty cells
- Fixes for Icarousel responsive
- Fixed user notifications for "Static content Text and Register" element
- Fixed twitter responsive issues
- Fixed numbers of forecast days in SC - Weather panel
- Accordion ID not generated properly
- Fixed Iosslider video controls
- Fixed height for portfolio carousels responsiveness
- Fixed fancy slider responsive issues
- Fixed Flexslider nav/bullets disable options
- Fixed Custom menu activates all items
- Fixes PHP Fatal Error
- Fixed documentation styles
- Fix for screenshot box not to start carousel if 1 item only

UPDATE / 13 Apr. 2016 / Intermediary update

- Enabled automatic updates.

UPDATE / 13 Apr. 2016 / Intermediary update

- Fixed WP 4.5 bug causing multiple problems (eg: responsive menu, page builder not working etc.)
- Fixed Laptop slider (having extra closing div)
- Fixed Icarousel slider's sizes

UPDATE / 10 Feb. 2016 / Intermediary update

- Fixed search notices/warnings
- Fixed Shop Products Presentation not displaying items from Latest si Best-selling tabs
- escaped title in iosslider captions
- Images in Devices element, mobile view
- Columns in icon boxes grid, mobile view
- Notice Undefined index: title
- Some slugs in "help" type fields in general options
- Fixed position of search panel dropdown on mobile
- Fixed missing category in breadcrumb
- Fixed product main image on hover, issue with srcset
- Fixed sortable portfolio ordering issue
- Fixed Mini-cart panel's buttons text color
- Fixed portfolio slider glitch on mobiles

- Allow child theme to override the default login redirect url
- Prevent server caching for zn_dynamic.css
- Contact Form - refresh page after sending a message
- Retina Favicon. In v4.0.12 we'll remove the Favicon option due to WordPress's built-in favicon system ( Customizer > Site identity > Site Icon ).

UPDATE 4.0.11 / 04 Feb. 2016

General overall code improvements and cleanup

- Bug caused by menu, conflicting with Page builder.
- Automatic updates notifications not being displayed
- Weather script in Static content Weather element
- Icon shortcode
- Bug preventing removal of subheader styles
- Cart Panel view on mobile
- Header components misalignment on Iphone 6 (IOS)
- Small fix to mega-menu's submenu when hovering
- Historic element date label position
- Show cart to visitors option
- Automatically re-center Google Map when changing from portrait to landscape view
- Default subheader is applied by default to Custom Subheader element
- Custom HTML bad formatting
- Header width (jumping to 1200 when viewport smaller than defined width)
- Modal image target bug
- Portfolio dynamic fields not being wrapped into list.

- General improvements to string translations
- Compatibility with Sensei plugin from WooThemes
- Improved URLs code with zn_extract_link() ensuring proper title display to URLs
- Removed WPK folder from theme and improved code distribution inside the theme

- Multiple options dependencies for options (framework)
- Added Modal Inline Dynamic type, pass title attribute to field in contact form (Good solution for passing a link's title to a contact form. In a group of elements with links, one single modal form should be created and it'll receive the dynamic title value )
- Magnific popup, simple class for links called "mfp-image" for triggering modal images.

- Theme translation files

UPDATE 4.0.10 / 27.01.2016

General overall code improvements and cleanup

- Options for search forms to search for WC products
- Header width option
- Header options available for all styles - Header position (relative/absolute), height, custom background styling, alpha-colored background
- Custom dynamic rows for portfolio items
- Extra options for Sortable portfolio - Load more button, show/hide toolbars or item description, sort type options
- Rgba support for colorpickers
- New Call To Action style - Custom all-styles-available & dynamic (up to 3 buttons)
- Icon support for tabs nav
- Option to debug contact form easily
- Option for Custom Subheader element to inherit Height & Padding from "Unlimited header" style
- All bottom masks for default subheader style and unlimited subh.
- Added and improved existing page options, with custom code (HTML, CSS and JS)
- Margin & padding options for custom container
- Custom styling for YITH Ajax navigation plugin
- Multiple columns display for blog posts (in blog post page)
- Language selector multiple styles
- Register button in header and other options
- Very simple style of Team member element

- Content being added to Horizontal & Vertical tabs always going to Tab #1
- WooCommerce Archive element - 3 columns float problem
- One-page demo layout - All menu items have active class
- iCarousel display
- Search page sidebar problems
- Column options not visible in horizontal tabs element
- Prevent "division by 0" notice when there is no regular price set
- Content checks for Infocard (Logo)
- Modals in responsive menus
- Contact form small issues
- Subheader component fixes and improvements
- Sample data importing not working on PHP7
- Search query - now properly accepting portfolio items but also other post types added with or without page builder
- Fixed statistics element odd/even placement
- Breadcrumb doesn't display SHOP nor BLOG
- Sliding top panel when scrolling page with sticky header
- Flickr feed widget limit option
- Custom CSS saving issues
- Sale amount option problems
- Support for Youtube short url
- Equalizator spacing padding for boxed layout
- Fixed light/dark colors for elements.
- Sidebar titles if using "special characters"

- Refactored entire CSS, improved it and selectors quality.
- Re-built entire header part of the theme, now overridable and much more easier to customize in child-theme, through file override or hooks.
- Spelling errors
- Allowing the Flash Sale badge to be overridden in the child theme
- Cute Slider plugin, better resources management
- Kallyas Dashboard with Server data & recommendations
- Switched custom container's bg to alpha colorpicker
- Set the modal ajax url to always use the framework variable
- Grid image gallery element to prevent isotope load on demand (adding "stop-isotope" custom class to element)
- SSL improvements and compatibility issues
- RTL layout improvements
- Improved page title customizability through filter in child theme
- Added max-height for Cart Pop-up to prevent scrolling issues with sticky header
- Code quality for Theme Check plugin

- Google fonts list
- Updated EN language files
- Revolution Slider

- Featured boxes page builder element (use icon boxes elements)
- Infobox page builder element (use custom section and buttons element)
- Services boxes page builder element (use Service box page builder element)
- Shop features page builder element (use section and icon boxes instead)
- Static content page builder element (use section with video background instead)
- "zn_active_item_classes" function

Click here to see the full changelog of Kallyas Theme
0.00 星 0 星



  1. UPDATE 4.1.3 / 26 APR. 2016

    Fixed fatal error on older PHP versions (causing issues when accessing Admin)

ZIY 会员微信群