1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  4
                                  4
                                  4
                                  4
                                  8
                                  6
                                  6
                                  12

                                  The default grid system provided in Bootstrap utilizes 12 columns that render out at widths of 724px, 940px (default without responsive CSS included), and 1170px. Below 767px viewports, the columns become fluid and stack vertically.

                                  <div class="row">
                                      <div class="span4">...</div>
                                      <div class="span8">...</div>
                                  </div>
                                  

                                  As shown here, a basic layout can be created with two "columns", each spanning a number of the 12 foundational columns we defined as part of our grid system.

                                  Offsetting columns

                                  4
                                  4 offset 4
                                  3 offset 3
                                  3 offset 3
                                  8 offset 4
                                  <div class="row">
                                    <div class="span4">...</div>
                                    <div class="span4 offset4">...</div>
                                  </div>
                                  

                                  Nesting columns

                                  With the static (non-fluid) grid system in Bootstrap, nesting is easy. To nest your content, just add a new .row and set of .span* columns within an existing .span* column.

                                  Example

                                  Nested rows should include a set of columns that add up to the number of columns of it's parent. For example, two nested .span3 columns should be placed within a .span6.

                                  Level 1 of column
                                  Level 2
                                  Level 2
                                  <div class="row">
                                    <div class="span6">
                                      Level 1 column
                                      <div class="row">
                                        <div class="span3">Level 2</div>
                                        <div class="span3">Level 2</div>
                                      </div>
                                    </div>
                                  </div>
                                  

                                  Fluid columns

                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  1
                                  4
                                  4
                                  4
                                  4
                                  8
                                  6
                                  6
                                  12

                                  Percents, not pixels

                                  The fluid grid system uses percents for column widths instead of fixed pixels. It also has the same responsive variations as our fixed grid system, ensuring proper proportions for key screen resolutions and devices.

                                  Fluid rows

                                  Make any row fluid simply by changing .row to .row-fluid. The columns stay the exact same, making it super straightforward to flip between fixed and fluid layouts.

                                  Markup

                                  <div class="row-fluid">
                                    <div class="span4">...</div>
                                    <div class="span8">...</div>
                                  </div>
                                  

                                  Fluid nesting

                                  Nesting with fluid grids is a bit different: the number of nested columns doesn't need to match the parent. Instead, your columns are reset at each level because each row takes up 100% of the parent column.

                                  Fluid 12
                                  Fluid 6
                                  Fluid 6
                                  <div class="row-fluid">
                                    <div class="span12">
                                      Level 1 of column
                                      <div class="row-fluid">
                                        <div class="span6">Level 2</div>
                                        <div class="span6">Level 2</div>
                                      </div>
                                    </div>
                                  </div>
                                  
                                  Variable Default value Description
                                  @gridColumns 12 Number of columns
                                  @gridColumnWidth 60px Width of each column
                                  @gridGutterWidth 20px Negative space between columns

                                  Variables in LESS

                                  Built into Bootstrap are a handful of variables for customizing the default 940px grid system, documented above. All variables for the grid are stored in variables.less.

                                  How to customize

                                  Modifying the grid means changing the three @grid* variables and recompiling Bootstrap. Change the grid variables in variables.less and use one of the four ways documented to recompile. If you're adding more columns, be sure to add the CSS for those in grid.less.

                                  Staying responsive

                                  Customization of the grid only works at the default level, the 940px grid. To maintain the responsive aspects of Bootstrap, you'll also have to customize the grids in responsive.less.

                                  Fixed layout

                                  The default and simple 940px-wide, centered layout for just about any website or page provided by a single <div class="container">.

                                  <body>
                                    <div class="container">
                                      ...
                                    </div>
                                  </body>
                                  

                                  Fluid layout

                                  <div class="container-fluid"> gives flexible page structure, min- and max-widths, and a left-hand sidebar. It's great for apps and docs.

                                  <div class="container-fluid">
                                    <div class="row-fluid">
                                      <div class="span2">
                                        <!--Sidebar content-->
                                      </div>
                                      <div class="span10">
                                        <!--Body content-->
                                      </div>
                                    </div>
                                  </div>
                                  

                                  Responsive devices

                                  What they do

                                  Media queries allow for custom CSS based on a number of conditions—ratios, widths, display type, etc—but usually focuses around min-width and max-width.

                                  • Modify the width of column in our grid
                                  • Stack elements instead of float wherever necessary
                                  • Resize headings and text to be more appropriate for devices

                                  Use media queries responsibly and only as a start to your mobile audiences. For larger projects, do consider dedicated code bases and not layers of media queries.

                                  Supported devices

                                  Bootstrap supports a handful of media queries in a single file to help make your projects more appropriate on different devices and screen resolutions. Here's what's included:

                                  Label Layout width Column width Gutter width
                                  Smartphones 480px and below Fluid columns, no fixed widths
                                  Smartphones to tablets 767px and below Fluid columns, no fixed widths
                                  Portrait tablets 768px and above 42px 20px
                                  Default 980px and up 60px 20px
                                  Large display 1200px and up 70px 30px

                                  Requires meta tag

                                  To ensure devices display responsive pages properly, include the viewport meta tag.

                                  <meta name="viewport" content="width=device-width, initial-scale=1.0">

                                  Using the media queries

                                  Bootstrap doesn't automatically include these media queries, but understanding and adding them is very easy and requires minimal setup. You have a few options for including the responsive features of Bootstrap:

                                  1. Use the compiled responsive version, bootstrap-responsive.css
                                  2. Add @import "responsive.less" and recompile Bootstrap
                                  3. Modify and recompile responsive.less as a separate file

                                  Why not just include it? Truth be told, not everything needs to be responsive. Instead of encouraging developers to remove this feature, we figure it best to enable it.

                                    /* Landscape phones and down */
                                    @media (max-width: 480px) { ... }
                                  
                                    /* Landscape phone to portrait tablet */
                                    @media (max-width: 767px) { ... }
                                  
                                    /* Portrait tablet to landscape and desktop */
                                    @media (min-width: 768px) and (max-width: 979px) { ... }
                                  
                                    /* Large desktop */
                                    @media (min-width: 1200px) { ... }
                                  

                                  Responsive utility classes

                                  What are they

                                  For faster mobile-friendly development, use these basic utility classes for showing and hiding content by device.

                                  When to use

                                  Use on a limited basis and avoid creating entirely different versions of the same site. Instead, use them to complement each device's presentation.

                                  For example, you might show a <select> element for nav on mobile layouts, but not on tablets or desktops.

                                  Support classes

                                  Shown here is a table of the classes we support and their effect on a given media query layout (labeled by device). They can be found in responsive.less.

                                  Class Phones 480px and below Tablets 767px and below Desktops 768px and above
                                  .visible-phone Visible
                                  .visible-tablet Visible
                                  .visible-desktop Visible
                                  .hidden-phone Visible Visible
                                  .hidden-tablet Visible Visible
                                  .hidden-desktop Visible Visible

                                  Test case

                                  Resize your browser or load on different devices to test the above classes.

                                  Visible on...

                                  Green checkmarks indicate that class is visible in your current viewport.

                                  • Phone✔ Phone
                                  • Tablet✔ Tablet
                                  • Desktop✔ Desktop

                                  Hidden on...

                                  Here, green checkmarks indicate that class is hidden in your current viewport.

                                  • Phone✔ Phone
                                  • Tablet✔ Tablet
                                  • Desktop✔ Desktop


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