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

/// ---------------------------------------------------------------------------
/// Search
/// ---------------------------------------------------------------------------

/// Application search
.md-search {
  position: relative;

  /// Search overlay
  &__overlay {
    display: none;

    /// [mobile -]: Only show overlay on mobile
    @include break-to-device(mobile) {
      display: block;
      position: absolute;
      top: 0.4rem;
      left: 0.4rem;
      width: 4.0rem;
      height: 4.0rem;
      transform-origin: center;
      transition: transform 0.3s 0.1s,
                  opacity   0.2s 0.2s;
      border-radius: 100%;
      background: #EEEEEE;
      opacity: 0;
      overflow: hidden;
      z-index: 0;

      /// Expanded overlay
      .md-toggle--search:checked ~ .md-header & {
        transform: scale(40);
        transition: transform 0.4s,
                    opacity   0.1s;
        opacity: 1;
        z-index: 1;
      }
    }
  }

  /// Inner wrapper
  &__inner {
    padding: 0.8rem 0.8rem 0;

    /// [tablet +]: Header-embedded search
    @include break-from-device(tablet) {
      padding: 0.4rem;
    }
  }

  /// Search form
  &__form {
    position: relative;
    border-radius: px2rem(2px);
    text-align: right;

    /// [mobile -]: Add drop-shadow on mobile
    @include break-to-device(mobile) {
      @include z-depth(2);
    }
  }

  /// Icon
  &__icon {
    position: absolute;
    top: 0.8rem;
    left: 1.2rem;
    transition: color 0.25s;
    font-size: 2.4rem;
    cursor: pointer;

    /// [mobile -]: Use back arrow as search icon
    @include break-to-device(mobile) {
      top: 1.2rem;

      /// Hack: @extend doesn't work in media queries, so override manually
      &::before {
        content: "arrow_back";
      }
    }
  }

  /// Search field
  &__input {
    padding: 0 0.8rem 0 6.4rem;
    border-radius: px2rem(2px);

    /// Placeholder and icon color in active state
    + .md-search__icon,
    &::placeholder {
      color: $md-color-black--light;
    }

    /// [mobile -]: Full-screen search bar
    @include break-to-device(mobile) {
      width: 100%;
      height: 4.8rem;
      font-size: 1.8rem;
    }

    /// [tablet +]: Header-embedded search
    @include break-from-device(tablet) {
      width: 23.0rem;
      height: 4.0rem;
      padding-left: 4.8rem;
      transition: width            0.25s cubic-bezier(0.1, 0.7, 0.1, 1.0),
                  background-color 0.25s,
                  color            0.25s;
      background: $md-color-white--lightest;
      color: $md-color-white;
      font-size: ms(0);

      /// Placeholder color
      + .md-search__icon,
      &::placeholder {
        transition: color 0.25s;
        color: $md-color-white;
      }

      /// Active search field
      &:focus {
        width: 40.0rem;
        background: $md-color-white;
        color: $md-color-black;

        /// Placeholder and icon color in active state
        + .md-search__icon,
        &::placeholder {
          color: $md-color-black--light;
        }
      }
    }
  }
}