Use em for controls

sass/elements/content.sass

@@ -24,30 +24,36 @@
   h5,
   h6
     color: $text-strong
-    font-weight: 300
+    font-weight: $weight-title-normal
     line-height: 1.125
-    margin-bottom: 20px
-  h1,
-  h2,
-  h3
+  h1
+    font-size: 2em
+    margin-bottom: 0.5em
     &:not(:first-child)
-      margin-top: 40px
+      margin-top: 1em
+  h2
+    font-size: 1.75em
+    margin-bottom: 0.5714em
+    &:not(:first-child)
+      margin-top: 1.1428em
+  h3
+    font-size: 1.5em
+    margin-bottom: 0.6666em
+    &:not(:first-child)
+      margin-top: 1.3333em
+  h4
+    font-size: 1.25em
+    margin-bottom: 0.8em
+  h5
+    font-size: 1.125em
+    margin-bottom: 0.8888em
+  h6
+    font-size: 1em
+    margin-bottom: 1em
   blockquote
     background-color: $background
     border-left: 5px solid $border
-    padding: 1.5em
-  h1
-    font-size: 2em
-  h2
-    font-size: 1.75em
-  h3
-    font-size: 1.5em
-  h4
-    font-size: 1.25em
-  h5
-    font-size: 1.125em
-  h6
-    font-size: 1em
+    padding: 1.25em 1.5em
   ol
     list-style: decimal outside
     margin-left: 2em
@@ -64,11 +70,9 @@
       ul
         list-style-type: square
   // Sizes
+  &.is-small
+    font-size: $size-small
   &.is-medium
-    font-size: $size-5
-    code
-      font-size: $size-6
+    font-size: $size-medium
   &.is-large
-    font-size: $size-4
-    code
-      font-size: $size-5
+    font-size: $size-large