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

////
/// Copyright (c) 2016-2017 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: fixed;
  top: 0;
  right: 0;
  left: 0;
  height: 4.8rem;
  transition:
    background-color 0.25s,
    color 0.25s;
  background-color: $md-color-primary;
  color: $md-color-white;
  box-shadow: none;
  z-index: 2;
  // Hack: putting the header on the GPU avoids unnecessary repaints
  backface-visibility: hidden;

  // Always show 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 0.25s,
      color 0.25s,
      box-shadow 0.25s;
    box-shadow:
      0 0      0.4rem rgba(0, 0, 0, 0.1),
      0 0.4rem 0.8rem rgba(0, 0, 0, 0.2);
  }

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

// Navigation within header
.md-header-nav {
  padding: 0 0.4rem;

  // Icon buttons
  &__button {
    @extend %md-icon__button;

    position: relative;
    transition: opacity 0.25s;
    z-index: 1;

    // Hovered icon
    &:hover {
      opacity: 0.7;
    }

    // Set correct display on image or icon
    &.md-logo * {
      display: block;
    }

    // Hide search icon, if JavaScript is not available.
    .no-js &.md-icon--search {
      display: none;
    }

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

      // Search icon
      &.md-icon--search {
        display: none;
      }
    }

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

      // Home icon or logo
      &.md-icon--home,
      &.md-logo {
        display: none;
      }
    }

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

      // Menu icon
      &.md-icon--menu {
        display: none;
      }
    }
  }

  // Header topics
  &__topic {
    display: block;
    position: absolute;
    transition:
      transform 0.4s cubic-bezier(0.1, 0.7, 0.1, 1),
      opacity   0.15s;
    text-overflow: ellipsis;
    white-space: nowrap;
    overflow: hidden;

    // Page title
    & + & {
      transform: translateX(2.5rem);
      transition:
        transform 0.4s cubic-bezier(1, 0.7, 0.1, 0.1),
        opacity   0.15s;
      opacity: 0;
      z-index: -1;
      pointer-events: none;
    }

    // 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 {
    padding: 0 2rem;
    font-size: 1.8rem;
    line-height: 4.8rem;

    // Show page title
    &[data-md-state="active"] .md-header-nav__topic {
      transform: translateX(-2.5rem);
      transition:
        transform 0.4s cubic-bezier(1, 0.7, 0.1, 0.1),
        opacity   0.15s;
      opacity: 0;
      z-index: -1;
      pointer-events: none;

      // Page title
      & + .md-header-nav__topic {
        transform: translateX(0);
        transition:
          transform 0.4s cubic-bezier(0.1, 0.7, 0.1, 1),
          opacity   0.15s;
        opacity: 1;
        z-index: 0;
        pointer-events: initial;
      }
    }
  }

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

    // [tablet landscape +]: Show the reposistory from tablet
    @include break-from-device(tablet landscape) {
      display: block;
      width: 23rem;
      max-width: 23rem;
      margin-left: 2.8rem;
      padding-right: 1.2rem;
    }
  }
}