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
 * IN THE SOFTWARE.
 */

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

/*
 * Scope in content for greater specificity
 */
.md-content {

  /*
   * Permalink
   */
  .headerlink {
    display: inline-block;
    margin-left: 1.0rem;
    opacity: 0;
    color: $md-color-black--lighter;
    transform: translate3d(0, 0.5rem, 0);
    transition: opacity  .125s .25s,
                transform .25s .25s,
                color     .25s;
  }

  /*
   * Only show permalinks in hover state
   */
  h1, h2, h3, h4, h5, h6 {
    &:hover .headerlink {
      margin-left: 1.0rem;
      opacity: 1;
      transform: translate3d(0, 0, 0);

      /*
       * Active link
       */
      &:hover {
        color: $md-color-accent;
      }
    }
  }
}