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

// Tabs with outline
.md-tabs {
  width: 100%;
  transition: background 0.25s;
  background: mix($md-color-primary, $md-color-black, 75%);
  overflow: auto;

  // [tablet -]: Hide tabs for tablet and below, as they don't make any sense
  @include break-to-device(tablet) {
    display: none;
  }

  // List of items
  &__list {
    margin: 0;
    margin-left: 0.4rem;
    padding: 0;
    list-style: none;
    white-space: nowrap;
  }

  // List item
  &__item {
    display: inline-block;
    height: 4.8rem;
    padding-right: 1.2rem;
    padding-left: 1.2rem;
  }

  // Link inside item - could be defined as block elements and aligned via
  // line height, but this would imply more repaints when scrolling
  &__link {
    display: block;
    margin-top: 1.6rem;
    transition:
      color 0.25s,
      transform 0.4s cubic-bezier(0.1, 0.7, 0.1, 1),
      opacity 0.1s;
    color: $md-color-white--light;
    font-size: 1.4rem;

    // Active or hovered link
    &--active,
    &:hover {
      color: $md-color-white;
    }

    // Delay transitions by a small amount
    @for $i from 2 through 16 {
      .md-tabs__item:nth-child(#{$i}) & {
        transition-delay: 0.02s * ($i - 1);
      }
    }
  }

  // Fade-out tabs background upon scrolling
  &[data-md-state="hidden"] {
    background: $md-color-primary;

    // Hide tabs upon scrolling - disable transition to minimizes repaints whilte
    // scrolling down, while scrolling up seems to be okay
    .md-tabs__link {
      transform: translateY(50%);
      transition:
        color 0.25s,
        transform 0s 0.4s,
        opacity 0.1s;
      opacity: 0;
    }
  }

  // [screen +]: Adjust main navigation styles
  @include break-from-device(screen) {

    // Hide 1st level nested items, as they are listed in the tabs by setting
    // font-size to zero, as we need to preserve bottom padding
    ~ .md-main .md-nav--primary > .md-nav__list > .md-nav__item--nested {
      font-size: 0;
    }

    // We're on the 2nd+ level
    &--active ~ .md-main {

      // Adjust 1st level styles
      .md-nav--primary {

        // Hide site title
        .md-nav__title--site {
          display: none;
        }

        // Hide 1st level normal items
        & > .md-nav__list > .md-nav__item {
          font-size: 0;

          // Show 1st level nested items and induce margin collapse
          &--nested {
            font-size: 1.4rem;
            overflow: auto;

            // Render link same as main navigation title
            > .md-nav__link {
              margin-top: 1.2rem;
              font-weight: 700;
              pointer-events: none;

              // Hide icon for expansion
              &::after {
                display: none;
              }
            }
          }
        }
      }

      // Always expand nested navigation on 2nd level
      .md-nav[data-md-level="1"] {
        max-height: initial;

        // Remove left spacing on 2nd level items
        > .md-nav__list > .md-nav__item {
          padding-left: 0;
        }
      }
    }
  }
}