mkdocs-material/src/assets/stylesheets/layout/_header.scss

////
/// Copyright (c) 2016-2020 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
////

// ----------------------------------------------------------------------------
// Rules
// ----------------------------------------------------------------------------

// Application header (stays always on top)
.md-header {
  position: sticky;
  top: 0;
  right: 0;
  left: 0;
  height: px2rem(48px);
  transition:
    background-color 250ms,
    color 250ms;
  background-color: var(--md-color-primary);
  color: var(--md-color-background);
  box-shadow: none;
  z-index: 2;
  // Hack: putting the header on the GPU avoids unnecessary repaints
  backface-visibility: hidden;

  // Always hide shadow, in case JavaScript is not available
  .no-js & {
    transition: none;
    box-shadow: none;
  }

  // Show and animate shadow
  &[data-md-state="shadow"] {
    transition:
      background-color 250ms,
      color            250ms,
      box-shadow       250ms;
    box-shadow:
      0 0           px2rem(4px) rgba(0, 0, 0, 0.1),
      0 px2rem(4px) px2rem(8px) rgba(0, 0, 0, 0.2);
  }

  // Hide for print
  @media print {
    display: none;
  }
}

// Navigation within header
.md-header-nav {
  display: flex;
  padding: 0 px2rem(4px);

  // Icon buttons
  &__button {
    position: relative;
    transition: opacity 250ms;
    z-index: 1;

    // Adjust for right-to-left languages
    [dir="rtl"] & {

      // Flip icon vertically
      svg {
        transform: scaleX(-1);
      }
    }

    // Focused or hovered icon
    &:focus,
    &:hover {
      opacity: 0.7;
    }

    // Logo
    &.md-logo {
      margin: px2rem(4px);
      padding: px2rem(8px);

      // Image or icon
      img,
      svg {
        display: block;
        width: px2rem(24px);
        height: px2rem(24px);
        fill: currentColor;
      }
    }

    // Hide search icon, if JavaScript is not available.
    .no-js &[for="__search"] {
      display: none;
    }

    // [tablet landscape +]: Hide the search button
    @include break-from-device(tablet landscape) {

      // Search button
      &[for="__search"] {
        display: none;
      }
    }

    // [tablet -]: Hide the logo
    @include break-to-device(tablet) {

      // Logo
      &.md-logo {
        display: none;
      }
    }

    // [screen +]: Hide the menu button
    @include break-from-device(screen) {

      // Menu button
      &[for="__drawer"] {
        display: none;
      }
    }
  }

  // Header topics
  &__topic {
    display: block;
    position: absolute;
    width: 100%;
    padding: 0 px2rem(20px);
    transition:
      transform 400ms cubic-bezier(0.1, 0.7, 0.1, 1),
      opacity   150ms;
    text-overflow: ellipsis;
    white-space: nowrap;
    overflow: hidden;

    // Page title
    & + & {
      transform: translateX(px2rem(25px));
      transition:
        transform 400ms cubic-bezier(1, 0.7, 0.1, 0.1),
        opacity   150ms;
      opacity: 0;
      z-index: -1;
      pointer-events: none;

      // Adjust for right-to-left languages
      [dir="rtl"] & {
        transform: translateX(px2rem(-25px));
      }
    }

    // Induce ellipsis, if no JavaScript is available
    .no-js & {
      position: initial;
    }

    // Hide page title as it is invisible anyway and will overflow the header
    .no-js & + & {
      display: none;
    }
  }

  // Header title - set line height to match icon for correct alignment
  &__title {
    flex-grow: 1;
    font-size: px2rem(18px);
    line-height: px2rem(48px);

    // Show page title
    &[data-md-state="active"] .md-header-nav__topic {
      transform: translateX(px2rem(-25px));
      transition:
        transform 400ms cubic-bezier(1, 0.7, 0.1, 0.1),
        opacity   150ms;
      opacity: 0;
      z-index: -1;
      pointer-events: none;

      // Adjust for right-to-left languages
      [dir="rtl"] & {
        transform: translateX(px2rem(25px));
      }

      // Page title
      & + .md-header-nav__topic {
        transform: translateX(0);
        transition:
          transform 400ms cubic-bezier(0.1, 0.7, 0.1, 1),
          opacity   150ms;
        opacity: 1;
        z-index: 0;
        pointer-events: initial;
      }
    }

    // Patch ellipsis
    > .md-header-nav__ellipsis {
      position: relative;
      width: 100%;
      height: 100%;
    }
  }

  // Repository containing source
  &__source {
    display: none;

    // [tablet landscape +]: Show the reposistory from tablet
    @include break-from-device(tablet landscape) {
      display: block;
      width: px2rem(234px);
      max-width: px2rem(234px);
      margin-left: px2rem(20px);

      // Adjust for right-to-left languages
      [dir="rtl"] & {
        margin-right: px2rem(20px);
        margin-left: initial;
      }
    }

    // [screen +]: Increase spacing of search bar
    @include break-from-device(screen) {
      margin-left: px2rem(28px);

      // Adjust for right-to-left languages
      [dir="rtl"] & {
        margin-right: px2rem(28px);
      }
    }
  }
}