css Audio - Active file-generic CSS - Active Generic - Active HTML - Active JS - Active SVG - Active Text - Active file-generic Video - Active header Love html icon-new-collection icon-person icon-team numbered-list123 pop-out spinner split-screen star tv

Pen Settings

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Use npm Packages

We can make npm packages available for you to use in your JavaScript. We use webpack to prepare them and make them available to import. We'll also process your JavaScript with Babel.

⚠️ This feature can only be used by logged in users.

Code Indentation

     

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <h1 class="title">
  The responsive-font-size mixin
</h1>

<article class="article">
  <h2 class="article__title">
    Automated font-size rescaling with SCSS
  </h2>
  <p class="article__date">
    2017/12/21
  </p>
  <p class="article__content">
    This text automatically rescales thanks to the <a href="https://github.com/MartijnCuppens/postcss-rfs">RFS mixin</a>. It uses the RFS algorithm to automatically calculate the appropriate font size based on the dimensions of the monitor or device.
  </p>
</article>
<article class="article">
  <h2 class="article__title">PostCSS alternative</h2>
  <p class="article__content">
      A <a href="https://github.com/MartijnCuppens/postcss-rfs" target="_blank">PostCSS plugin</a> is available which uses the <code>responsive-font-size</code> property.<br>
    <i>
    <b>Update:</b> In the meanwhile the PostCSS plugin is also included in the main RFS project.
    </i>
    </p>
</article>
<article class="article">
  <h2 class="article__title">RFS in Bootstrap?</h2>
  <p class="article__content">Currenty there is an open feature-request to put RFS in Bootstrap: <a href="https://github.com/twbs/bootstrap/issues/23053">Responsive font sizes</a>. The result of RFS in Bootstrap is shown on <a href="http://martijncuppens.github.io/rfs/">the bootstrap RFS demo site</a>.<br>
    <i>
    <b>Update:</b> In the meanwhile RFS is also included in Bootstrap.
  </i>
    </p>
</article>
<article class="article disable-responsive-font-size">
  <h2 class="article__title">Disable responsive font-size</h2>
  <div class="article__content">Responsive font-sizing can be disabled within an element by adding the <code>.disable-responsive-font-size</code> class
  <br>
    <i>
    <b>Update:</b> In the meanwhile this feature is disabled by default because it generates more css. You can enable it by setting <code>$rfs-class: "disable"</code> in scss.
  </i>
  </div>
</article>
<article class="article">
  <h2 class="article__title">Lorem ipsum text</h2>
  <div class="article__content">No demo without Lorem ipsum text. Lorem ipsum dolor sit amet, consectetur adipisicing elit. Provident tenetur delectus fuga et, doloribus rerum! Aperiam voluptate mollitia rerum necessitatibus repudiandae asperiores doloremque deleniti praesentium,
    dolorem maxime, quia, libero. Maiores? Lorem ipsum dolor sit amet, consectetur adipisicing elit. Iste distinctio quidem, obcaecati aperiam! Distinctio porro pariatur labore veniam deserunt mollitia consectetur unde voluptatem blanditiis eaque aperiam,
    sequi sed vero debitis!</div>
</article>
            
          
!
            
              // See https://github.com/twbs/rfs

// Configuration

// Base font size
$rfs-base-font-size: 1.25rem !default;
$rfs-font-size-unit: rem !default;

// Breakpoint at where font-size starts decreasing if screen width is smaller
$rfs-breakpoint: 1200px !default;
$rfs-breakpoint-unit: px !default;

// Resize font-size based on screen height and width
$rfs-two-dimensional: false !default;

// Factor of decrease
$rfs-factor: 10 !default;

@if type-of($rfs-factor) != "number" or $rfs-factor <= 1 {
  @error "`#{$rfs-factor}` is not a valid  $rfs-factor, it must be greater than 1.";
}

// Generate enable or disable classes. Possibilities: false, "enable" or "disable"
$rfs-class: false !default;

// 1 rem = $rfs-rem-value px
$rfs-rem-value: 16 !default;

// Safari iframe resize bug: https://github.com/twbs/rfs/issues/14
$rfs-safari-iframe-resize-bug-fix: false !default;

// Disable RFS by setting $enable-responsive-font-sizes to false
$enable-responsive-font-sizes: true !default;

// Cache $rfs-base-font-size unit
$rfs-base-font-size-unit: unit($rfs-base-font-size);

// Remove px-unit from $rfs-base-font-size for calculations
@if $rfs-base-font-size-unit == "px" {
  $rfs-base-font-size: $rfs-base-font-size / ($rfs-base-font-size * 0 + 1);
}
@else if $rfs-base-font-size-unit == "rem" {
  $rfs-base-font-size: $rfs-base-font-size / ($rfs-base-font-size * 0 + 1 / $rfs-rem-value);
}

// Cache $rfs-breakpoint unit to prevent multiple calls
$rfs-breakpoint-unit-cache: unit($rfs-breakpoint);

// Remove unit from $rfs-breakpoint for calculations
@if $rfs-breakpoint-unit-cache == "px" {
  $rfs-breakpoint: $rfs-breakpoint / ($rfs-breakpoint * 0 + 1);
}
@else if $rfs-breakpoint-unit-cache == "rem" or $rfs-breakpoint-unit-cache == "em" {
  $rfs-breakpoint: $rfs-breakpoint / ($rfs-breakpoint * 0 + 1 / $rfs-rem-value);
}

// Responsive font-size mixin
@mixin rfs($fs, $important: false) {
  // Cache $fs unit
  $fs-unit: if(type-of($fs) == "number", unit($fs), false);

  // Add !important suffix if needed
  $rfs-suffix: if($important, " !important", "");

  // If $fs isn't a number (like inherit) or $fs has a unit (not px or rem, like 1.5em) or $ is 0, just print the value
  @if not $fs-unit or $fs-unit != "" and $fs-unit != "px" and $fs-unit != "rem" or $fs == 0 {
    font-size: #{$fs}#{$rfs-suffix};
  }
  @else {
    // Variables for storing static and fluid rescaling
    $rfs-static: null;
    $rfs-fluid: null;

    // Remove px-unit from $fs for calculations
    @if $fs-unit == "px" {
      $fs: $fs / ($fs * 0 + 1);
    }
    @else if $fs-unit == "rem" {
      $fs: $fs / ($fs * 0 + 1 / $rfs-rem-value);
    }

    // Set default font-size
    @if $rfs-font-size-unit == rem {
      $rfs-static: #{$fs / $rfs-rem-value}rem#{$rfs-suffix};
    }
    @else if $rfs-font-size-unit == px {
      $rfs-static: #{$fs}px#{$rfs-suffix};
    }
    @else {
      @error "`#{$rfs-font-size-unit}` is not a valid unit for $rfs-font-size-unit. Use `px` or `rem`.";
    }

    // Only add media query if font-size is bigger as the minimum font-size
    // If $rfs-factor == 1, no rescaling will take place
    @if $fs > $rfs-base-font-size and $enable-responsive-font-sizes {
      $min-width: null;
      $variable-unit: null;

      // Calculate minimum font-size for given font-size
      $fs-min: $rfs-base-font-size + ($fs - $rfs-base-font-size) / $rfs-factor;

      // Calculate difference between given font-size and minimum font-size for given font-size
      $fs-diff: $fs - $fs-min;

      // Base font-size formatting
      // No need to check if the unit is valid, because we did that before
      $min-width: if($rfs-font-size-unit == rem, #{$fs-min / $rfs-rem-value}rem, #{$fs-min}px);

      // If two-dimensional, use smallest of screen width and height
      $variable-unit: if($rfs-two-dimensional, vmin, vw);

      // Calculate the variable width between 0 and $rfs-breakpoint
      $variable-width: #{$fs-diff * 100 / $rfs-breakpoint}#{$variable-unit};

      // Set the calculated font-size.
      $rfs-fluid: calc(#{$min-width} + #{$variable-width}) #{$rfs-suffix};
    }

    // Rendering
    @if $rfs-fluid == null {
      // Only render static font-size if no fluid font-size is available
      font-size: $rfs-static;
    }
    @else {
      $mq-value: null;

      // RFS breakpoint formatting
      @if $rfs-breakpoint-unit == em or $rfs-breakpoint-unit == rem {
        $mq-value: #{$rfs-breakpoint / $rfs-rem-value}#{$rfs-breakpoint-unit};
      }
      @else if $rfs-breakpoint-unit == px {
        $mq-value: #{$rfs-breakpoint}px;
      }
      @else {
        @error "`#{$rfs-breakpoint-unit}` is not a valid unit for $rfs-breakpoint-unit. Use `px`, `em` or `rem`.";
      }

      @if $rfs-class == "disable" {
        // Adding an extra class increases specificity,
        // which prevents the media query to override the font size
        &,
        .disable-responsive-font-size &,
        &.disable-responsive-font-size {
          font-size: $rfs-static;
        }
      }
      @else {
        font-size: $rfs-static;
      }

      @if $rfs-two-dimensional {
        @media (max-width: #{$mq-value}), (max-height: #{$mq-value}) {
          @if $rfs-class == "enable" {
            .enable-responsive-font-size &,
            &.enable-responsive-font-size {
              font-size: $rfs-fluid;
            }
          }
          @else {
            font-size: $rfs-fluid;
          }

          @if $rfs-safari-iframe-resize-bug-fix {
            // stylelint-disable-next-line length-zero-no-unit
            min-width: 0vw;
          }
        }
      }
      @else {
        @media (max-width: #{$mq-value}) {
          @if $rfs-class == "enable" {
            .enable-responsive-font-size &,
            &.enable-responsive-font-size {
              font-size: $rfs-fluid;
            }
          }
          @else {
            font-size: $rfs-fluid;
          }

          @if $rfs-safari-iframe-resize-bug-fix {
            // stylelint-disable-next-line length-zero-no-unit
            min-width: 0vw;
          }
        }
      }
    }
  }
}

// The font-size & responsive-font-size mixin uses RFS to rescale font sizes
@mixin font-size($fs, $important: false) {
  @include rfs($fs, $important);
}

@mixin responsive-font-size($fs, $important: false) {
  @include rfs($fs, $important);
}





/////////////
// Theming //
/////////////
html {
  background: #DDD;
}

body {
  max-width: 1200px;
  padding: 20px;
  margin: 0 auto;
  line-height: 1.2;
}

.title{
  @include font-size(4rem);
  margin: 0 0 .5em;
}

.article{
  background: white;
  box-shadow: 0 0 10px rgba(black, .25);
  padding: 20px 25px;
  
  &:not(:first-of-type){
    margin-top: 20px;
  }
  
  &__title{
    @include font-size(27px);
    margin: 0;
  }
  
  &__date{
    padding-top: .25em;
    @include font-size(12);
    opacity: .75;
    font-style: italic;
  }
  
  &__content{
    padding-top: .75em;
    @include font-size(16);
    margin: 0;
    line-height: 1.4;
  }
}
            
          
!
999px
🕑 One or more of the npm packages you are using needs to be built. You're the first person to ever need it! We're building it right now and your preview will start updating again when it's ready.
Loading ..................

Console