diff --git a/scss/vendor/_rfs.scss b/scss/vendor/_rfs.scss
index 497e07eda9..43f19ca160 100644
--- a/scss/vendor/_rfs.scss
+++ b/scss/vendor/_rfs.scss
@@ -2,9 +2,9 @@
 
 // SCSS RFS mixin
 //
-// Automated font-resizing
+// Automated responsive font sizes
 //
-// See https://github.com/twbs/rfs
+// Licensed under MIT (https://github.com/twbs/rfs/blob/master/LICENSE)
 
 // Configuration
 
@@ -12,11 +12,19 @@
 $rfs-base-font-size: 1.25rem !default;
 $rfs-font-size-unit: rem !default;
 
+@if $rfs-font-size-unit != rem and $rfs-font-size-unit != px {
+  @error "`#{$rfs-font-size-unit}` is not a valid unit for $rfs-font-size-unit. Use `px` or `rem`.";
+}
+
 // 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
+@if $rfs-breakpoint-unit != px and $rfs-breakpoint-unit != em and $rfs-breakpoint-unit != rem {
+  @error "`#{$rfs-breakpoint-unit}` is not a valid unit for $rfs-breakpoint-unit. Use `px`, `em` or `rem`.";
+}
+
+// Resize font size based on screen height and width
 $rfs-two-dimensional: false !default;
 
 // Factor of decrease
@@ -60,7 +68,49 @@ $rfs-breakpoint-unit-cache: unit($rfs-breakpoint);
   $rfs-breakpoint: $rfs-breakpoint / ($rfs-breakpoint * 0 + 1 / $rfs-rem-value);
 }
 
-// Responsive font-size mixin
+// Internal mixin that adds disable classes to the selector if needed.
+@mixin _rfs-disable-class {
+  @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 {
+      @content;
+    }
+  }
+  @else {
+    @content;
+  }
+}
+
+// Internal mixin that adds enable classes to the selector if needed.
+@mixin _rfs-enable-class {
+  @if $rfs-class == "enable" {
+    .enable-responsive-font-size &,
+    &.enable-responsive-font-size {
+      @content;
+    }
+  }
+  @else {
+    @content;
+  }
+}
+
+// Internal mixin used to determine which media query needs to be used
+@mixin _rfs-media-query($mq-value) {
+  @if $rfs-two-dimensional {
+    @media (max-width: #{$mq-value}), (max-height: #{$mq-value}) {
+      @content;
+    }
+  }
+  @else {
+    @media (max-width: #{$mq-value}) {
+      @content;
+    }
+  }
+}
+
+// Responsive font size mixin
 @mixin rfs($fs, $important: false) {
   // Cache $fs unit
   $fs-unit: if(type-of($fs) == "number", unit($fs), false);
@@ -73,11 +123,7 @@ $rfs-breakpoint-unit-cache: unit($rfs-breakpoint);
     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
+    // Remove unit from $fs for calculations
     @if $fs-unit == "px" {
       $fs: $fs / ($fs * 0 + 1);
     }
@@ -85,116 +131,52 @@ $rfs-breakpoint-unit-cache: unit($rfs-breakpoint);
       $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};
+    // Set default font size
+    $rfs-static: if($rfs-font-size-unit == rem, #{$fs / $rfs-rem-value}rem, #{$fs}px);
+
+    // Only add the media query if the font size is bigger than the minimum font size
+    @if $fs <= $rfs-base-font-size or not $enable-responsive-font-sizes {
+      font-size: #{$rfs-static}#{$rfs-suffix};
     }
     @else {
-      @error "`#{$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
+      // Calculate the minimum font size for $fs
       $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
+      // Calculate difference between $fs and the minimum 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
+      // Use `vmin` if two-dimensional is enabled
       $variable-unit: if($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.
+      // 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;
+      // Breakpoint formatting
+      $mq-value: if($rfs-breakpoint-unit == px, #{$rfs-breakpoint}px, #{$rfs-breakpoint / $rfs-rem-value}#{$rfs-breakpoint-unit});
 
-      // 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 $rfs-breakpoint-unit. Use `px`, `em` or `rem`.";
+      @include _rfs-disable-class {
+        font-size: #{$rfs-static}#{$rfs-suffix};
       }
 
-      @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: $rfs-static;
+      @include _rfs-media-query($mq-value) {
+        @include _rfs-enable-class {
+          font-size: $rfs-fluid;
         }
-      }
-      @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 $rfs-safari-iframe-resize-bug-fix {
-            // stylelint-disable-next-line length-zero-no-unit
-            min-width: 0vw;
-          }
-        }
+        // Include safari iframe resize fix if needed
+        min-width: if($rfs-safari-iframe-resize-bug-fix, (0 * 1vw), null);
       }
     }
   }
 }
 
-// The font-size & responsive-font-size mixin uses RFS to rescale font sizes
+// The font-size & responsive-font-size mixins use RFS to rescale the font size
 @mixin font-size($fs, $important: false) {
   @include rfs($fs, $important);
 }