mkdocs-material/src/assets/stylesheets/main/layout/_nav.scss

////
/// Copyright (c) 2016-2021 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
// ----------------------------------------------------------------------------

// Navigation variables
:root {
  --md-nav-icon--prev: svg-load("material/arrow-left.svg");
  --md-nav-icon--next: svg-load("material/chevron-right.svg");
  --md-toc-icon: svg-load("material/table-of-contents.svg");
}

// ----------------------------------------------------------------------------

// Navigation
.md-nav {
  font-size: px2rem(14px);
  line-height: 1.3;

  // Navigation title
  &__title {
    display: block;
    padding: 0 px2rem(12px);
    overflow: hidden;
    font-weight: 700;
    text-overflow: ellipsis;

    // Navigaton button
    .md-nav__button {
      display: none;

      // Stretch images based on height, as it's the smaller dimension
      img {
        width: auto;
        height: 100%;
      }

      // Button with logo, pointing to `config.site_url`
      &.md-logo {

        // Image or icon
        :where(img, svg) {
          display: block;
          width: px2rem(48px);
          height: px2rem(48px);
          fill: currentColor;
        }
      }
    }
  }

  // Navigation list
  &__list {
    margin: 0;
    padding: 0;
    list-style: none;
  }

  // Navigation item
  &__item {
    padding: 0 px2rem(12px);

    // Navigation item on level 2
    & & {
      padding-inline-end: 0;
    }
  }

  // Navigation link
  &__link {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 0.625em;
    overflow: hidden;
    text-overflow: ellipsis;
    cursor: pointer;
    transition: color 125ms;
    scroll-snap-align: start;

    // Navigation link in blurred state
    &[data-md-state="blur"] {
      color: var(--md-default-fg-color--light);
    }

    // Active link
    .md-nav__item &--active {
      color: var(--md-typeset-a-color);
    }

    // Stretch section index link to full width
    .md-nav__item &--index [href] {
      width: 100%;
    }

    // Navigation link on focus/hover
    &:is(:focus, :hover) {
      color: var(--md-accent-fg-color);
    }

    // Show outline for keyboard devices
    &.focus-visible {
      outline-color: var(--md-accent-fg-color);
      outline-offset: px2rem(4px);
    }

    // Navigation link for table of contents
    .md-nav--primary &[for="__toc"] {
      display: none;

      // Table of contents icon
      .md-icon::after {
        display: block;
        width: 100%;
        height: 100%;
        mask-image: var(--md-toc-icon);
        background-color: currentColor;
      }

      // Hide table of contents
      ~ .md-nav {
        display: none;
      }
    }

    // Navigation link children (for section indexes)
    > * {
      display: flex;
      cursor: pointer;
    }
  }

  // Navigation icon
  &__icon {
    flex-shrink: 0;
  }

  // Repository information container
  &__source {
    display: none;
  }

  // [tablet -]: Layered navigation
  @include break-to-device(tablet) {

    // Primary and nested navigation
    &--primary,
    &--primary & {
      position: absolute;
      top: 0;
      inset-inline: 0;
      z-index: 1;
      display: flex;
      flex-direction: column;
      height: 100%;
      background-color: var(--md-default-bg-color);
    }

    // Primary navigation
    &--primary {

      // Navigation title and item
      :where(.md-nav__title, .md-nav__item) {
        font-size: px2rem(16px);
        line-height: 1.5;
      }

      // Navigation title
      .md-nav__title {
        position: relative;
        height: px2rem(112px);
        padding: px2rem(60px) px2rem(16px) px2rem(4px);
        color: var(--md-default-fg-color--light);
        font-weight: 400;
        line-height: px2rem(48px);
        white-space: nowrap;
        background-color: var(--md-default-fg-color--lightest);
        cursor: pointer;

        // Navigation icon
        .md-nav__icon {
          position: absolute;
          top: px2rem(8px);
          inset-inline-start: px2rem(8px);
          display: block;
          width: px2rem(24px);
          height: px2rem(24px);
          margin: px2rem(4px);

          // Navigation icon in link to previous level
          &::after {
            display: block;
            width: 100%;
            height: 100%;
            background-color: currentColor;
            mask-image: var(--md-nav-icon--prev);
            mask-repeat: no-repeat;
            mask-size: contain;
            content: "";
          }
        }

        // Navigation list
        ~ .md-nav__list {
          overflow-y: auto;
          background-color: var(--md-default-bg-color);
          box-shadow:
            0 px2rem(1px) 0 var(--md-default-fg-color--lightest) inset;
          scroll-snap-type: y mandatory;
          touch-action: pan-y;

          // Omit border on first child
          > :first-child {
            border-top: 0;
          }
        }

        // Top-level navigation title
        &[for="__drawer"] {
          color: var(--md-primary-bg-color);
          font-weight: 700;
          background-color: var(--md-primary-fg-color);
        }

        // Button with logo, pointing to `config.site_url`
        .md-logo {
          position: absolute;
          top: px2rem(4px);
          inset-inline-start: px2rem(4px);
          display: block;
          margin: px2rem(4px);
          padding: px2rem(8px);
        }
      }

      // Navigation list
      .md-nav__list {
        flex: 1;
      }

      // Navigation item
      .md-nav__item {
        padding: 0;
        border-top: px2rem(1px) solid var(--md-default-fg-color--lightest);

        // Navigation link in active navigation
        &--active > .md-nav__link {
          color: var(--md-typeset-a-color);

          // Navigation link on focus/hover
          &:where(:focus, :hover) {
            color: var(--md-accent-fg-color);
          }
        }
      }

      // Navigation link
      .md-nav__link {
        margin-top: 0;
        padding: px2rem(12px) px2rem(16px);

        // Navigation icon
        .md-nav__icon {
          width: px2rem(24px);
          height: px2rem(24px);
          margin-inline-end: px2rem(-4px);
          font-size: px2rem(24px);

          // Navigation icon in link to next level
          &::after {
            display: block;
            width: 100%;
            height: 100%;
            background-color: currentColor;
            mask-image: var(--md-nav-icon--next);
            mask-repeat: no-repeat;
            mask-size: contain;
            content: "";
          }
        }
      }

      // Flip icon vertically
      .md-nav__icon {

        // Adjust for right-to-left languages
        [dir="rtl"] &::after {
          transform: scale(-1);
        }
      }

      // Table of contents contained in primary navigation
      .md-nav--secondary {

        // Navigation on level 2-6
        .md-nav {
          position: static;
          background-color: transparent;

          // Navigation link on level 3
          .md-nav__link {
            padding-inline-start: px2rem(28px);
          }

          // Navigation link on level 4
          .md-nav .md-nav__link {
            padding-inline-start: px2rem(40px);
          }

          // Navigation link on level 5
          .md-nav .md-nav .md-nav__link {
            padding-inline-start: px2rem(52px);
          }

          // Navigation link on level 6
          .md-nav .md-nav .md-nav .md-nav__link {
            padding-inline-start: px2rem(64px);
          }
        }
      }
    }

    // Table of contents
    &--secondary {
      background-color: transparent;
    }

    // Toggle for nested navigation
    &__toggle ~ & {
      display: flex;
      transform: translateX(100%);
      opacity: 0;
      transition:
        transform 250ms cubic-bezier(0.8, 0, 0.6, 1),
        opacity   125ms 50ms;

      // Adjust for right-to-left languages
      [dir="rtl"] & {
        transform: translateX(-100%);
      }
    }

    // Show nested navigation when toggle is active
    &__toggle:checked ~ & {
      transform: translateX(0);
      opacity: 1;
      transition:
        transform 250ms cubic-bezier(0.4, 0, 0.2, 1),
        opacity   125ms 125ms;

      // Navigation list
      > .md-nav__list {
        // Hack: promote to own layer to reduce jitter
        backface-visibility: hidden;
      }
    }
  }

  // [tablet portrait -]: Layered navigation with table of contents
  @include break-to-device(tablet portrait) {

    // Show link to table of contents
    &--primary &__link[for="__toc"] {
      display: flex;

      // Show table of contents icon
      .md-icon::after {
        content: "";
      }

      // Hide navigation link to current page
      + .md-nav__link {
        display: none;
      }

      // Show table of contents
      ~ .md-nav {
        display: flex;
      }
    }

    // Repository information container
    &__source {
      display: block;
      padding: 0 px2rem(4px);
      color: var(--md-primary-bg-color);
      background-color: var(--md-primary-fg-color--dark);
    }
  }

  // [tablet landscape]: Layered navigation with table of contents
  @include break-at-device(tablet landscape) {

    // Show link to integrated table of contents
    &--integrated &__link[for="__toc"] {
      display: flex;

      // Show table of contents icon
      .md-icon::after {
        content: "";
      }

      // Hide navigation link to current page
      + .md-nav__link {
        display: none;
      }

      // Show table of contents
      ~ .md-nav {
        display: flex;
      }
    }
  }

  // [tablet landscape +]: Tree-like table of contents
  @include break-from-device(tablet landscape) {

    // Navigation title
    &--secondary &__title {

      // Adjust snapping behavior
      &[for="__toc"] {
        scroll-snap-align: start;
      }

      // Hide navigation icon
      .md-nav__icon {
        display: none;
      }
    }
  }

  // [screen +]: Tree-like navigation
  @include break-from-device(screen) {
    transition: max-height 250ms cubic-bezier(0.86, 0, 0.07, 1);

    // Navigation title
    &--primary &__title {

      // Adjust snapping behavior
      &[for="__drawer"] {
        scroll-snap-align: start;
      }

      // Hide navigation icon
      .md-nav__icon {
        display: none;
      }
    }

    // Hide toggle for nested navigation
    &__toggle ~ & {
      display: none;
    }

    // Show nested navigation when toggle is active or indeterminate
    &__toggle:where(:checked, :indeterminate) ~ & {
      display: block;
    }

    // Hide navigation title in nested navigation
    &__item--nested > & > &__title {
      display: none;
    }

    // Navigation section
    &__item--section {
      display: block;
      margin: 1.25em 0;

      // Adjust spacing on last child
      &:last-child {
        margin-bottom: 0;
      }

      // Show navigation link as title
      > .md-nav__link {
        font-weight: 700;
        pointer-events: none;

        // Make navigation link clickable
        &--index [href] {
          pointer-events: initial;
        }

        // Hide naviation icon
        .md-nav__icon {
          display: none;
        }
      }

      // Navigation
      > .md-nav {
        display: block;

        // Adjust spacing on next level item
        > .md-nav__list > .md-nav__item {
          padding: 0;
        }
      }
    }

    // Navigation icon
    &__icon {
      float: right;
      width: px2rem(18px);
      height: px2rem(18px);
      transition: transform 250ms;

      // Adjust for right-to-left languages
      [dir="rtl"] & {
        float: left;
        transform: rotate(180deg);
      }

      // Navigation icon content
      &::after {
        display: inline-block;
        width: 100%;
        height: 100%;
        vertical-align: px2rem(-2px);
        background-color: currentColor;
        mask-image: var(--md-nav-icon--next);
        mask-repeat: no-repeat;
        mask-size: contain;
        content: "";
      }

      // Navigation icon - rotate icon when toggle is active or indeterminate
      .md-nav__item--nested .md-nav__toggle:checked ~ .md-nav__link &,
      .md-nav__item--nested .md-nav__toggle:indeterminate ~ .md-nav__link & {
        transform: rotate(90deg);
      }
    }

    // Modifier for when navigation tabs are rendered
    &--lifted {

      // Hide nested level 0 navigation items and site title
      > .md-nav__list > .md-nav__item--nested,
      > .md-nav__title {
        display: none;
      }

      // Hide level 0 navigation items
      > .md-nav__list > .md-nav__item {
        display: none;

        // Active parent navigation item
        &--active {
          display: block;
          padding: 0;

          // Show navigation link as title
          > .md-nav__link {
            margin-top: 0;
            padding: 0 px2rem(12px);
            font-weight: 700;
            pointer-events: none;

            // Make navigation link clickable
            &--index [href] {
              pointer-events: initial;
            }

            // Hide naviation icon
            .md-nav__icon {
              display: none;
            }
          }
        }
      }

      // Hack: Always show active navigation tab on breakpoint screen, despite
      // of checkbox being checked or not. Fixes #1655.
      .md-nav[data-md-level="1"] {
        display: block;

        // Adjust spacing for level 1 navigation items
        > .md-nav__list > .md-nav__item {
          padding-inline-end: px2rem(12px);
        }
      }
    }

    // Modifier for when table of contents is rendered in primary navigation
    &--integrated > .md-nav__list > .md-nav__item--active {

      // Add spacing to container for non-nested navigation items
      &:not(.md-nav__item--nested) {
        padding: 0 px2rem(12px);

        // Remove padding as it's given by container
        > .md-nav__link {
          padding: 0;
        }
      }

      // Show integrated table of contents
      .md-nav--secondary {
        display: block;
        margin-bottom: 1.25em;
        border-inline-start: px2rem(1px) solid var(--md-primary-fg-color);

        // Hide table of contents title
        > .md-nav__title {
          display: none;
        }
      }
    }
  }
}