diff --git a/_sass/2017/base/base.scss b/_sass/2017/base/base.scss
index 6f2a0c36a..662b38193 100644
--- a/_sass/2017/base/base.scss
+++ b/_sass/2017/base/base.scss
@@ -11,6 +11,7 @@ html, body {
 }
 
 body {
+  @include font-size(0);
   padding: 8px;
   margin: 0 auto;
 }
@@ -24,6 +25,11 @@ body {
 
 pre, code {
   font-family: $monospace-font;
+  letter-spacing: -0.03em;
+}
+
+pre {
+  font-size: 0.92em;
 }
 
 * {
diff --git a/_sass/2017/components/h2-section.scss b/_sass/2017/components/h2-section.scss
index 46d5f5fbb..28849cf6d 100644
--- a/_sass/2017/components/h2-section.scss
+++ b/_sass/2017/components/h2-section.scss
@@ -4,10 +4,6 @@
 
 /* Hide the first h2 heading */
 .h2-section {
-  & > h2 {
-    margin-top: 64px;
-  }
-
   &:first-child > h2 {
     display: none;
   }
diff --git a/_sass/2017/components/h3-section.scss b/_sass/2017/components/h3-section.scss
index a2bbe9011..5e3bf4663 100644
--- a/_sass/2017/components/h3-section.scss
+++ b/_sass/2017/components/h3-section.scss
@@ -6,16 +6,27 @@
   & > pre {
     margin: 0;
     padding: 16px;
-    font-size: 12px;
   }
 
   & {
     background: white;
     box-shadow:
-      0 6px 8px rgba(80, 100, 150, 0.07),
-      0 2px 3px rgba(80, 100, 150, 0.15);
+      0 6px 8px rgba(80, 100, 150, 0.06),
+      0 1px 2px rgba(80, 100, 150, 0.30);
   }
 
+  @media (max-width: 480px) {
+    margin: 0 -16px;
+    box-shadow:
+      0 1px 1px rgba(80, 100, 150, 0.30);
+  }
+}
+
+/*
+ * Children
+ */
+
+.h3-section > .body {
   /* Lists */
   & > ul {
     margin: 0;
@@ -24,7 +35,7 @@
   }
 
   & > ul > li {
-    padding: 16px;
+    padding: 8px;
     padding-left: 32px + 4px;
     position: relative;
   }
@@ -38,7 +49,7 @@
     background: $gray-text;
     border-radius: 50%;
     left: 16px;
-    top: 24px + 2px;
+    top: 16px + 2px;
   }
 
   & > ul > li + li {
@@ -78,6 +89,10 @@
   }
 }
 
+/*
+ * Prime
+ */
+
 .h3-section.-prime > .body {
   border-radius: 2px;
   box-shadow:
diff --git a/_sass/2017/markdown/headings.scss b/_sass/2017/markdown/headings.scss
index 630a8e6b9..865827bdc 100644
--- a/_sass/2017/markdown/headings.scss
+++ b/_sass/2017/markdown/headings.scss
@@ -11,16 +11,32 @@
   padding: 0;
   margin-bottom: 16px;
   padding-bottom: 16px;
+  margin-top: 64px;
   border-bottom: solid 1px $line-color;
+
+  @media (max-width: 768px) {
+    margin: $gutter / 2;
+    margin-bottom: 8px;
+    margin-top: 32px;
+    padding-bottom: 8px;
+  }
+
+  @media (max-width: 480px) {
+    margin: $gutter / 4;
+    margin-bottom: 8px;
+    margin-top: 32px;
+    padding-bottom: 8px;
+  }
 }
 
 .main-heading,
 .MarkdownBody h1 {
-  font-size: 3.2em;
+  @include font-size(6);
+  margin-top: 0;
 }
 
 .MarkdownBody h2 {
-  font-size: 2.4em;
+  @include font-size(5);
 }
 
 .MarkdownBody h3 {
@@ -28,7 +44,7 @@
   padding: 0;
   margin-bottom: 16px;
   font-family: $body-font;
-  font-size: 1.66em;
+  @include font-size(2);
   font-weight: 300;
   color: $baseA-400;
 }
diff --git a/_sass/2017/style.scss b/_sass/2017/style.scss
index 74db425dc..a114490b3 100644
--- a/_sass/2017/style.scss
+++ b/_sass/2017/style.scss
@@ -11,12 +11,21 @@ $text-color: #333;
 $baseA-400: #53a;
 $baseB-400: #35a;
 $baseB-600: adjust-color($baseB-400, $lightness: 20%, $hue: -20deg);
-$line-color: rgba(50, 80, 150, 0.1);
+$line-color: rgba(50, 80, 150, 0.07);
 $dark-line-color: rgba(50, 80, 150, 0.2);
 
+$modularscale: (
+  base: 14px, ratio: 1.2,
+  480px: (base: 13px, ratio: 1.15),
+  768px: (base: 14px, ratio: 1.17),
+  1280px: (base: 14px, ratio: 1.2)
+);
+
 @import url('https://unpkg.com/sanitize.css@5.0.0/sanitize.css');
 @import url('https://fonts.googleapis.com/css?family=Fira+Mono:400');
 
+@import './utils/modularscale';
+@import './utils/font-size';
 @import './base/base';
 @import './markdown/headings';
 @import './markdown/table';
diff --git a/_sass/2017/utils/_font-size.scss b/_sass/2017/utils/_font-size.scss
new file mode 100644
index 000000000..d9252549a
--- /dev/null
+++ b/_sass/2017/utils/_font-size.scss
@@ -0,0 +1,3 @@
+@mixin font-size ($n) {
+  @include ms-respond(font-size, $n);
+}
diff --git a/_sass/2017/utils/_modularscale.scss b/_sass/2017/utils/_modularscale.scss
new file mode 100644
index 000000000..3c21f42cc
--- /dev/null
+++ b/_sass/2017/utils/_modularscale.scss
@@ -0,0 +1,312 @@
+// https://github.com/modularscale/modularscale-sass v3.0.3
+
+// Ratios
+$double-octave    : 4                 ;
+$pi               : 3.14159265359     ;
+$major-twelfth    : 3                 ;
+$major-eleventh   : 2.666666667       ;
+$major-tenth      : 2.5               ;
+$octave           : 2                 ;
+$major-seventh    : 1.875             ;
+$minor-seventh    : 1.777777778       ;
+$major-sixth      : 1.666666667       ;
+$phi              : 1.618034          ;
+$golden           : $phi              ;
+$minor-sixth      : 1.6               ;
+$fifth            : 1.5               ;
+$augmented-fourth : 1.41421           ;
+$fourth           : 1.333333333       ;
+$major-third      : 1.25              ;
+$minor-third      : 1.2               ;
+$major-second     : 1.125             ;
+$minor-second     : 1.066666667       ;
+
+// Base config
+$ms-base          : 1em       !default;
+$ms-ratio         : $fifth    !default;
+$modularscale     : ()        !default;// Parse settings starting with defaults.
+// Settings should cascade down like you would expect in CSS.
+// More specific overrides previous settings.
+
+@function ms-settings($b: false, $r: false, $t: false, $m: $modularscale) {
+  $base: $ms-base;
+  $ratio: $ms-ratio;
+  $thread: map-get($m, $t);
+
+  // Override with user settings
+  @if map-get($m, base) {
+    $base: map-get($m, base);
+  }
+  @if map-get($m, ratio) {
+    $ratio: map-get($m, ratio);
+  }
+
+  // Override with thread settings
+  @if $thread {
+    @if map-get($thread, base) {
+      $base: map-get($thread, base);
+    }
+    @if map-get($thread, ratio) {
+      $ratio: map-get($thread, ratio);
+    }
+  }
+
+  // Override with inline settings
+  @if $b {
+    $base: $b;
+  }
+  @if $r {
+    $ratio: $r;
+  }
+
+  @return $base $ratio;
+}// Sass does not have native pow() support so this needs to be added.
+// Compass and other libs implement this more extensively.
+// In order to keep this simple, use those when they are avalible.
+// Issue for pow() support in Sass: https://github.com/sass/sass/issues/684
+
+@function ms-pow($b,$e) {
+
+  // Return 1 if exponent is 0
+  @if $e == 0 {
+    @return 1;
+  }
+
+  // If pow() exists (compass or mathsass) use that.
+  @if function-exists('pow') {
+    @return pow($b,$e);
+  }
+
+  // This does not support non-integer exponents,
+  // Check and return an error if a non-integer exponent is passed.
+  @if (floor($e) != $e) {
+    @error '
+======================================================================
+Non-integer values are not supported in modularscale by default.
+
+Try using mathsass in your project to add non-integer scale support.
+https://github.com/terkel/mathsass
+======================================================================
+'
+  }
+
+  // Seed the return.
+  $ms-return: $b;
+
+  // Multiply or divide by the specified number of times.
+  @if $e > 0 {
+    @for $i from 1 to $e {
+      $ms-return: $ms-return * $b;
+    }
+  }
+  @if $e < 0 {
+    @for $i from $e through 0 {
+      $ms-return: $ms-return / $b;
+    }
+  }
+  @return $ms-return;
+}// Stripping units is not a best practice
+// This function should not be used elsewhere
+// It is used here because calc() doesn't do unit logic
+// AND target ratios use units as a hack to get a number.
+@function ms-unitless($val) {
+  @return ($val / ($val - $val + 1));
+}// Basic list sorting
+// Would like to replace with http://sassmeister.com/gist/30e4863bd03ce0e1617c
+// Unfortunately libsass has a bug with passing arguments into the min() funciton.
+
+@function ms-sort($l) {
+
+  // loop until the list is confirmed to be sorted
+  $sorted: false;
+  @while $sorted == false {
+
+    // Start with the assumption that the lists are sorted.
+    $sorted: true;
+
+    // Loop through the list, checking each value with the one next to it.
+    // Swap the values if they need to be swapped.
+    // Not super fast but simple and modular scale doesn't lean hard on sorting.
+    @for $i from 2 through length($l) {
+      $n1: nth($l,$i - 1);
+      $n2: nth($l,$i);
+
+      // If the first value is greater than the 2nd, swap them.
+      @if $n1 > $n2 {
+        $l: set-nth($l, $i, $n1);
+        $l: set-nth($l, $i - 1, $n2);
+
+        // The list isn't sorted and needs to be looped through again.
+        $sorted: false;
+      }
+    }
+  }
+
+  // Return the sorted list.
+  @return $l;
+}// No reason to have decimal pixel values,
+// normalize them to whole numbers.
+
+@function ms-round-px($r) {
+  @if unit($r) == 'px' {
+    @return round($r);
+  }
+  @return $r;
+}// Convert number string to number
+@function ms-to-num($n) {
+  $l: str-length($n);
+  $r: 0;
+  $m: str-index($n,'.');
+  @if $m == null {
+    $m: $l + 1;
+  }
+  // Loop through digits and convert to numbers
+  @for $i from 1 through $l {
+    $v: str-slice($n,$i,$i);
+    @if $v == '1' { $v: 1; }
+    @elseif $v == '2' { $v: 2; }
+    @elseif $v == '3' { $v: 3; }
+    @elseif $v == '4' { $v: 4; }
+    @elseif $v == '5' { $v: 5; }
+    @elseif $v == '6' { $v: 6; }
+    @elseif $v == '7' { $v: 7; }
+    @elseif $v == '8' { $v: 8; }
+    @elseif $v == '9' { $v: 9; }
+    @elseif $v == '0' { $v: 0; }
+    @else { $v: null; }
+    @if $v != null {
+      $m: $m - 1;
+      $r: $r + ms-pow(10,$m - 1) * $v;
+    } @else {
+      $l: $l - 1;
+    }
+  }
+  @return $r;
+}
+
+// Find a ratio based on a target value
+@function ms-target($t,$b) {
+  // Convert to string
+  $t: $t + '';
+  // Remove base units to calulate ratio
+  $b: ms-unitless(nth($b,1));
+  // Find where 'at' is in the string
+  $at: str-index($t,'at');
+
+  // Slice the value and target out
+  // and convert strings to numbers
+  $v: ms-to-num(str-slice($t,0,$at - 1));
+  $t: ms-to-num(str-slice($t,$at + 2));
+
+  // Solve the modular scale function for the ratio.
+  @return ms-pow(($v/$b),(1/$t));
+}@function ms-function($v: 0, $base: false, $ratio: false, $thread: false, $settings: $modularscale) {
+
+  // Parse settings
+  $ms-settings: ms-settings($base,$ratio,$thread,$settings);
+  $base: nth($ms-settings, 1);
+  $ratio: nth($ms-settings, 2);
+
+  // Render target values from settings.
+  @if unit($ratio) != '' {
+    $ratio: ms-target($ratio,$base)
+  }
+
+  // Fast calc if not multi stranded
+  @if(length($base) == 1) {
+    @return ms-round-px(ms-pow($ratio, $v) * $base);
+  }
+
+  // Create new base array
+  $ms-bases: nth($base,1);
+
+  // Normalize base values
+  @for $i from 2 through length($base) {
+    // initial base value
+    $ms-base: nth($base,$i);
+    // If the base is bigger than the main base
+    @if($ms-base > nth($base,1)) {
+      // divide the value until it aligns with main base.
+      @while($ms-base > nth($base,1)) {
+        $ms-base: $ms-base / $ratio;
+      }
+      $ms-base: $ms-base * $ratio;
+    }
+    // If the base is smaller than the main base.
+    @elseif ($ms-base < nth($base,1)) {
+      // pump up the value until it aligns with main base.
+      @while $ms-base < nth($base,1) {
+        $ms-base: $ms-base * $ratio;
+      }
+    }
+    // Push into new array
+    $ms-bases: append($ms-bases,$ms-base);
+  }
+
+  // Sort array from smallest to largest.
+  $ms-bases: ms-sort($ms-bases);
+
+  // Find step to use in calculation
+  $vtep: floor($v / length($ms-bases));
+  // Find base to use in calculation
+  $ms-base: round(($v / length($ms-bases) - $vtep) * length($ms-bases)) + 1;
+
+  @return ms-round-px(ms-pow($ratio, $vtep) * nth($ms-bases,$ms-base));
+}// Generate calc() function
+// based on Mike Riethmuller's Precise control over responsive typography
+// http://madebymike.com.au/writing/precise-control-responsive-typography/
+@function ms-fluid($val1: 1em, $val2: 1em, $break1: 0, $break2: 0) {
+  $diff: ms-unitless($val2) - ms-unitless($val1);
+
+  // v1 + (v2 - v1) * ( (100vw - b1) / b2 - b1 )
+  @return calc( #{$val1} + #{ms-unitless($val2) - ms-unitless($val1)} * ( ( 100vw - #{$break1}) / #{ms-unitless($break2) - ms-unitless($break1)} ) );
+}
+
+// Main responsive mixin
+@mixin ms-respond($prop, $val, $map: $modularscale) {
+  $base: $ms-base;
+  $ratio: $ms-ratio;
+
+  $first-write: true;
+  $last-break: null;
+
+  // loop through all settings with a breakpoint type value
+  @each $v, $s in $map {
+    @if type-of($v) == number {
+      @if unit($v) != '' {
+
+        // Write out the first value without a media query.
+        @if $first-write {
+          #{$prop}: ms-function($val, $thread: $v, $settings: $map);
+
+          // Not the first write anymore, reset to false to move on.
+          $first-write: false;
+          $last-break: $v;
+        }
+
+        // Write intermediate breakpoints.
+        @else {
+          @media (min-width: $last-break) and (max-width: $v) {
+            $val1: ms-function($val, $thread: $last-break, $settings: $map);
+            $val2: ms-function($val, $thread: $v, $settings: $map);
+            #{$prop}: ms-fluid($val1,$val2,$last-break,$v);
+          }
+          $last-break: $v;
+        }
+      }
+    }
+  }
+
+  // Write the last breakpoint.
+  @if $last-break {
+    @media (min-width: $last-break) {
+      #{$prop}: ms-function($val, $thread: $last-break, $settings: $map);
+    }
+  }
+}// To attempt to avoid conflicts with other libraries
+// all funcitons are namespaced with `ms-`.
+// However, to increase usability, a shorthand function is included here.
+
+@function ms($v: 0, $base: false, $ratio: false, $thread: false, $settings: $modularscale) {
+  @return ms-function($v, $base, $ratio, $thread, $settings);
+}
diff --git a/sass.md b/sass.md
index 7914f888a..1c1f5854c 100644
--- a/sass.md
+++ b/sass.md
@@ -11,7 +11,9 @@ layout: 2017/sheet
 
 ```scss
 $red: #833;
+```
 
+```scss
 body {
   color: $red;
 }
@@ -31,6 +33,13 @@ body {
 }
 ```
 
+### Comments
+
+```scss
+/* Block comments */
+// Line comments
+```
+
 ### Mixins
 
 ```scss
@@ -38,7 +47,9 @@ body {
   font-family: sans-serif;
   font-weight: bold;
 }
+```
 
+```scss
 h1 {
   @include heading-font;
 }
@@ -52,18 +63,34 @@ h1 {
 }
 ```
 
+```scss
+body {
+  @include font-size(2);
+}
+```
+
 ### Extend
 
 ```scss
 .button {
   ···
 }
+```
 
+```scss
 .push-button {
   @extend .button;
 }
 ```
 
+### Composing
+
+```scss
+@import './other_sass_file`;
+```
+
+The `.scss` or `.sass` extension is optional.
+
 ## Color functions
 
 ### rgba
@@ -77,7 +104,7 @@ rgba($color, .5)
 ### Mixing
 
 ```scss
-mix($a, $b, 10%)   /* 10% a, 90% b */
+mix($a, $b, 10%)   // 10% a, 90% b
 ```
 
 ### Modifying HSLA
@@ -95,20 +122,20 @@ grayscale($color)
 
 ```scss
 adjust-hue($color, 15deg)
-compliment($color)    /* like adjust-hue(_, 180deg) */
+compliment($color)    // like adjust-hue(_, 180deg)
 invert($color)
 ```
 
 ```scss
 adjust-hue($color, 15deg)
-compliment($color)    /* like adjust-hue(_, 180deg) */
+compliment($color)    // like adjust-hue(_, 180deg)
 invert($color)
 ```
 
 ```scss
-fade-in($color, .5)   /* aka opacify() */
-fade-out($color, .5)  /* aka transparentize() - halves the opacity */
-rgba($color, .5)      /* sets alpha to .5 */
+fade-in($color, .5)   // aka opacify()
+fade-out($color, .5)  // aka transparentize() - halves the opacity
+rgba($color, .5)      // sets alpha to .5
 ```
 
 ### Getting HSL values
@@ -117,26 +144,26 @@ rgba($color, .5)      /* sets alpha to .5 */
 hue($color)
 saturation($color)
 lightness($color)
-alpha($color)         /* aka opacity() */
+alpha($color)         // aka opacity()
 ```
 
 ### Adjustments
 
 ```scss
-/* Changes by fixed amounts */
+// Changes by fixed amounts
 adjust-color($color, $blue: 5)
-adjust-color($color, $lightness: -30%)   /* like darken(_, 30%) */
-adjust-color($color, $alpha: -0.4)       /* like fade-out(_, .4) */
-adjust-color($color, $hue: 30deg)        /* like adjust-hue(_, 15deg) */
+adjust-color($color, $lightness: -30%)   // like darken(_, 30%)
+adjust-color($color, $alpha: -0.4)       // like fade-out(_, .4)
+adjust-color($color, $hue: 30deg)        // like adjust-hue(_, 15deg)
 ```
 
 ```scss
-/* Changes via percentage */
+// Changes via percentage
 scale-color($color, $lightness: 50%)
 ```
 
 ```scss
-/* Changes one property completely */
+// Changes one property completely
 change-color($color, $hue: 180deg)
 change-color($color, $blue: 250)
 ```
@@ -159,15 +186,15 @@ to-lower-case(hello)
 
 ```scss
 str-length(hello world)
-str-slice(hello, 2, 5)      /* "ello" - it's 1-based, not 0-based */
-str-insert("abcd", "X", 1)  /* "Xabcd" */
+str-slice(hello, 2, 5)      // "ello" - it's 1-based, not 0-based
+str-insert("abcd", "X", 1)  // "Xabcd"
 ```
 
 ### Units
 
 ```scss
-unit(3em)        /* 'em' */
-unitless(100px)  /* false */
+unit(3em)        // 'em'
+unitless(100px)  // false
 ```
 
 ### Numbers
@@ -185,15 +212,15 @@ max(1, 2, 3)
 ```
 
 ```scss
-percentage(.5)   /* 50% */
-random(3)        /* 0..3 */
+percentage(.5)   // 50%
+random(3)        // 0..3
 ```
 
 ### Misc
 
 ```scss
-variable-exists(red)    /* checks for $red */
-mixin-exists(red-text)  /* checks for @mixin red-text */
+variable-exists(red)    // checks for $red
+mixin-exists(red-text)  // checks for @mixin red-text
 function-exists(redify)
 ```
 
@@ -202,8 +229,8 @@ global-variable-exists(red)
 ```
 
 ```scss
-selector-append('.menu', 'li', 'a')   /* .menu li a */
-selector-nest('.menu', '&:hover li')  /* .menu:hover li */
+selector-append('.menu', 'li', 'a')   // .menu li a
+selector-nest('.menu', '&:hover li')  // .menu:hover li
 selector-extend(...)
 selector-parse(...)
 selector-replace(...)
@@ -285,8 +312,8 @@ $i: 6;
 ### Interpolation
 
 ```scss
-.#{$klass} { ... }      /* Class */
-call($function-name)    /* Functions */
+.#{$klass} { ... }      // Class
+call($function-name)    // Functions
 
 @media #{$tablet}
 font: #{$size}/#{$line-height}
@@ -298,7 +325,7 @@ url("#{$background}.jpg")
 ```scss
 $list: (a b c);
 
-nth($list, 1)  /* starts with 1 */
+nth($list, 1)  // starts with 1
 length($list)
 
 @each $item in $list { ... }