add anchor links for headlines

src/icons/link.svg

@@ -0,0 +1,4 @@
+<!-- Generated by IcoMoon.io -->
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24">
+<title>link</title>
+<path d="M17.016 6.984q2.063 0 3.516 1.477t1.453 3.539-1.453 3.539-3.516 1.477h-4.031v-1.922h4.031q1.266 0 2.18-0.914t0.914-2.18-0.914-2.18-2.18-0.914h-4.031v-1.922h4.031zM8.016 12.984v-1.969h7.969v1.969h-7.969zM3.891 12q0 1.266 0.914 2.18t2.18 0.914h4.031v1.922h-4.031q-2.063 0-3.516-1.477t-1.453-3.539 1.453-3.539 3.516-1.477h4.031v1.922h-4.031q-1.266 0-2.18 0.914t-0.914 2.18z"></path></svg>

src/sass/_base.scss

@@ -30,8 +30,12 @@ h1,
 h2,
 h3,
 h4,
-h5 {
+h5,
+h6 {
   font-weight: $body-font-weight;
+  display: flex;
+  align-items: center;
+  text-align: center;
 }
 
 a {
@@ -217,6 +221,10 @@ img {
       content: "\1f82a";
     }
   }
+
+  &__anchor .icon {
+    color: $gray-400;
+  }
 }
 
 .gdoc-post {

src/sass/_shortcodes.scss

@@ -70,6 +70,10 @@
     min-width: $body-min-width * 0.66;
     padding: 0 $padding-16;
   }
+
+  .gdoc-page__anchor {
+    display: none;
+  }
 }
 
 // {{< button >}}