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

/// ---------------------------------------------------------------------------
/// Navigation
/// ---------------------------------------------------------------------------

/// Nested navigation
.md-nav {

  /// Set font sizes
  &,
  h3 {
    font-size: ms(-1);
    line-height: 1.2;
  }

  /// Table of contents
  &--toc {
    border-left: px2rem(4px) solid $md-color-primary;
  }

  /// List of items
  &__list {
    list-style: none;

    /// 2nd+ level list
    & & {
      margin-left: 1.2rem;
    }

    /// Hide list by default
    .md-nav__toggle ~ & {
      max-height: 0;
      overflow: hidden;
    }

    /// Expand list, if toggle is checked
    .md-nav__toggle:checked ~ & {
      max-height: 100%;
    }
  }

  /// List item
  &__item {
    margin: 0.8rem 0 0;
    line-height: 1.6rem;
  }

  /// Link inside item
  &__link {
    display: block;
    transition: color 0.125s;
    text-overflow: ellipsis;
    overflow: hidden;

    /// Marked item
    &--marked {
      color: $md-color-black--light;
    }

    /// Current or hovered item
    &:hover,
    &:active,
    &--active {
      color: $md-color-accent;
    }
  }
}