message: fix(aio): improve positioning of heading-anchors
diff: +.sidenav-content {
  h1, h2, h3, h4, h5, h6 {
  - .icon-link {
  - color: $darkgray;
  - vertical-align: middle;
  - visibility: hidden;
  - margin: 8px;
  - font: normal normal 24px 'Material Icons';
  + .mat-icon, .material-icons {
  + visibility: hidden;
  display: inline-block;
  - line-height: 1;
  - text-transform: none;
  - letter-spacing: normal;
  - word-wrap: normal;
  - white-space: nowrap;
  - direction: ltr;
  -
  - /* Support for all WebKit browsers. */
  - -webkit-font-smoothing: antialiased;
  - /* Support for Safari and Chrome. */
  - text-rendering: optimizeLegibility;
  -
  - /* Support for Firefox. */
  - -moz-osx-font-smoothing: grayscale;
  -
  - /* Support for IE. */
  - font-feature-settings: 'liga';
  + color: $mediumgray;
  + margin: 0 8px;
  + }
  - &:before { content: 'link'; }
  + &:hover {
  + .mat-icon, .material-icons {
  + visibility: visible;
  + }
  }
  a {
  @@ -35,8 +21,23 @@ h1, h2, h3, h4, h5, h6 {
  display: inline-block;
  vertical-align: middle;
  }
  + }
  - &:hover .icon-link {
  - visibility: visible
  + .l-sub-section {
  + h1, h2, h3, h4, h5, h6 {
  + a {
  + padding-right: 24px;
  + margin-left: -74px;
  + }
  + }
  + }
  +
  + .alert {
  + h1, h2, h3, h4, h5, h6 {
  + a {
  + padding-right: 40px;
  + margin-left: -90px;
  + }
  + }
  }
  }
  