You're looking at the documentation for Tailwind CSS v2.
Tailwind CSS on GitHub

Flex Shrink

Utilities for controlling how flex items shrink.

Default class reference

Class
Properties
flex-shrink-0flex-shrink: 0;
flex-shrinkflex-shrink: 1;

Shrink

Use flex-shrink to allow a flex item to shrink if needed:

<div class="flex ...">
  <div class="flex-grow w-16 h-16 ...">
    <!-- This item will grow or shrink as needed -->
  </div>
  <div class="flex-shrink w-64 h-16 ...">
    <!-- This item will shrink -->
  </div>
  <div class="flex-grow w-16 h-16 ...">
    <!-- This item will grow or shrink as needed -->
  </div>
</div>

Don't shrink

Use flex-shrink-0 to prevent a flex item from shrinking:

<div class="flex ...">
  <div class="flex-1 h-16 ...">
    <!-- This item will grow or shrink as needed -->
  </div>
  <div class="flex-shrink-0 h-16 w-32 ...">
    <!-- This item will not shrink below its initial size-->
  </div>
  <div class="flex-1 h-16 ...">
    <!-- This item will grow or shrink as needed -->
  </div>
</div>

Responsive

To control how a flex item shrinks at a specific breakpoint, add a {screen}: prefix to any existing utility class. For example, use md:flex-shrink-0 to apply the flex-shrink-0 utility at only medium screen sizes and above.

<div class="flex ...">
  <!-- ... -->
  <div class="flex-shrink md:flex-shrink-0 ...">
    Responsive flex item
  </div>
  <!-- ... -->
</div>

For more information about Tailwind’s responsive design features, check out the Responsive Design documentation.

Customizing

Shrink Values

By default, Tailwind provides two flex-shrink utilities. You change, add, or remove these by editing the theme.flexShrink section of your Tailwind config.

  // tailwind.config.js
  module.exports = {
    theme: {
      flexShrink: {
        '0': 0,
-       DEFAULT: 1,
+       DEFAULT: 2,
+       '1': 1,
      }
    }
  }

Variants

By default, only responsive variants are generated for flex shrink utilities.

You can control which variants are generated for the flex shrink utilities by modifying the flexShrink property in the variants section of your tailwind.config.js file.

For example, this config will also generate hover and focus variants:

  // tailwind.config.js
  module.exports = {
    variants: {
      extend: {
        // ...
+       flexShrink: ['hover', 'focus'],
      }
    }
  }

Disabling

If you don't plan to use the flex shrink utilities in your project, you can disable them entirely by setting the flexShrink property to false in the corePlugins section of your config file:

  // tailwind.config.js
  module.exports = {
    corePlugins: {
      // ...
+     flexShrink: false,
    }
  }