mkdocs-material/src/assets/stylesheets/extensions/_permalinks.scss

////
/// Copyright (c) 2016 Martin Donath <martin.donath@squidfunk.com>
///
/// Permission is hereby granted, free of charge, to any person obtaining a
/// copy of this software and associated documentation files (the "Software"),
/// to deal in the Software without restriction, including without limitation
/// the rights to use, copy, modify, merge, publish, distribute, sublicense,
/// and/or sell copies of the Software, and to permit persons to whom the
/// Software is furnished to do so, subject to the following conditions:
///
/// The above copyright notice and this permission notice shall be included in
/// all copies or substantial portions of the Software.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
/// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
/// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
/// DEALINGS
////

// ----------------------------------------------------------------------------
// Permalinks extension
// ----------------------------------------------------------------------------

// Scoped in typesetted content for greater specificity
.md-typeset {

  // Permalink
  .headerlink {
    display: inline-block;
    margin-left: 1.0rem;
    transform: translate(0, 0.5rem);
    transition: transform 0.25s  0.25s,
                color     0.25s,
                opacity   0.125s 0.25s;
    color: $md-color-black--lighter;
    opacity: 0;
  }

  // All headers with permalinks have ids
  [id] {

    // Make permalink visible on hover
    &:hover  .headerlink,
    &:target .headerlink,
    & .headerlink:focus {
      transform: translate(0, 0);
      opacity: 1;
    }

    // Active or targeted permalink
    &:hover  .headerlink:hover,
    &:target .headerlink,
    & .headerlink:focus {
      color: $md-color-accent;
    }
  }

  // Correct anchor offset of headlines
  @each $level, $delta in (
    h1: 3.0rem,
    h2: 0.2rem,
    h3: 0.4rem,
    h4: 0.6rem,
    h5: 1.0rem,
    h6: 1.0rem
  ) {
    #{$level}[id]::before {
      display: block;
      margin-top: -(5.6rem + 2.4rem + $delta);
      padding-top: (5.6rem + 2.4rem + $delta);
      content: "";
    }
  }
}