cullmann.io/themes/CodeIT/assets/css/_partial/_header.scss

header {
  width: 100%;
  z-index: 150;
  background-color: $header-background-color;
  @include transition(box-shadow 0.3s ease);

  [theme="dark"] & {
    background-color: $header-background-color-dark;
  }

  .logo {
    min-height: 1.5em;
    height: 1.5em;
    vertical-align: text-bottom;
  }

  .logo,
  .header-title-pre {
    padding-right: 0.25rem;
  }

  .header-title-post {
    padding-left: 0.25rem;
  }

  &:hover {
    @include box-shadow(0 0 1.5rem 0 rgba(0, 0, 0, 0.1));
  }
}

.header-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-sizing: border-box;
  width: 100%;
}

.header-title {
  font-family: $header-title-font-family;
  font-weight: bold;
  margin-right: 0.5rem;
  min-width: 10%;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  @include flex(10);
}

.menu .menu-item {
  position: relative;
}

.language-select {
  position: absolute;
  opacity: 0;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;

  &:hover {
    cursor: pointer;
  }
}

.search {
  position: relative;

  input {
    color: transparent;
    box-sizing: border-box;
    height: 2.5rem;
    width: 2.5rem;
    @include border-radius(0.5rem);
    border: none;
    outline: none;
    background-color: $header-background-color;
    vertical-align: baseline !important;
    @include transition(width 0.3s ease);

    [theme="dark"] & {
      background-color: $header-background-color-dark;
    }
  }

  @include placeholder(transparent);

  .search-button {
    margin: 0;
    position: absolute;
    left: auto;
    right: 1rem;
  }

  .search-toggle {
    left: 0.5rem;
    right: auto;
    top: -1.125rem;
    bottom: -1.125rem;
  }

  .search-loading {
    display: none;
  }

  .search-clear {
    display: none;
  }

  .open &,
  &.mobile {
    input {
      color: $global-font-color;
      background-color: $search-background-color;
      padding: 0 2rem 0 2rem;
    }

    [theme="dark"] & {
      input {
        color: $global-font-color-dark;
        background-color: $search-background-color-dark;
      }

      @include placeholder($global-font-secondary-color-dark);
    }

    @include placeholder($global-font-secondary-color);

    .search-button {
      color: $global-font-secondary-color;

      [theme="dark"] & {
        color: $global-font-secondary-color-dark;
      }
    }

    .search-clear:hover {
      color: #ff6b6b;
    }

    .search-toggle:hover {
      cursor: default;
    }
  }
}

.theme-switch i {
  @include transform(rotate(225deg));
}

#header-desktop {
  display: block;
  position: fixed;
  height: $header-height;
  line-height: $header-height;

  [header-desktop="normal"] & {
    position: static;
  }

  .header-wrapper {
    padding: 0 2rem 0 10vh;

    .header-title {
      font-size: $header-title-font-size;
    }

    .menu {
      overflow: hidden;
      white-space: nowrap;

      .menu-inner {
        float: right;
      }

      .menu-item {
        margin: 0 0.5rem;

        &.delimiter {
          border-left: 1.5px solid $global-font-color;

          [theme="dark"] & {
            border-left-color: $global-border-color-dark;
          }
        }

        &.language {
          margin-right: 0;
        }

        &.search {
          margin: 0 -0.5rem 0 0;
        }
      }

      a.active {
        font-weight: 900;
        color: $header-hover-color;

        [theme="dark"] & {
          color: $header-hover-color-dark;
        }
      }
    }
  }

  &.open .header-wrapper .menu .menu-item.search {
    margin: 0 0.25rem 0 0.5rem;

    input {
      width: 24rem;
    }
  }
}

#header-mobile {
  display: none;
  position: fixed;
  height: $header-height;
  line-height: $header-height;

  [header-mobile="normal"] & {
    position: static;
  }

  .header-container {
    padding: 0;
    margin: 0;

    .header-wrapper {
      padding: 0 1rem;
      font-size: 1.125rem;
      @include transition(margin-top 0.3s ease);

      .header-title {
        font-size: $header-title-font-size;
        max-width: 80%;
      }

      .menu-toggle {
        line-height: 4rem;
        cursor: pointer;
        @include transition(width 0.3s ease);

        span {
          display: block;
          background: $global-font-color;
          width: 1.5rem;
          height: 2px;
          @include border-radius(3px);
          @include transition(all 0.3s ease-in-out);

          [theme="dark"] & {
            background: $global-font-color-dark;
          }
        }

        span:nth-child(1) {
          margin-bottom: 0.5rem;
        }

        span:nth-child(3) {
          margin-top: 0.5rem;
        }

        &.active {
          span:nth-child(1) {
            @include transform(rotate(45deg) translate(0.4rem, 0.5rem));
          }

          span:nth-child(2) {
            opacity: 0;
          }

          span:nth-child(3) {
            @include transform(rotate(-45deg) translate(0.4rem, -0.5rem));
          }
        }
      }
    }

    .menu {
      text-align: center;
      background: $header-background-color;
      border-top: 2px solid $global-border-color;
      display: none;
      padding-top: 0.5rem;
      @include box-shadow(0 0.125rem 0.25rem rgba(0, 0, 0, 0.1));

      .search-wrapper {
        display: flex;
        justify-content: space-between;
        align-items: center;
        box-sizing: border-box;
        padding: ($header-height - 2.5rem) / 2 1rem;
        line-height: 2.5rem;
      }

      .search {
        flex-grow: 10;

        .algolia-autocomplete,
        input {
          width: 100%;
        }
      }

      .search-button {
        top: 0;
      }

      .search-cancel {
        display: none;
        margin-left: 0.75rem;
      }

      .menu-item {
        display: block;
        line-height: 2.5rem;
      }

      &.active {
        display: block;
      }

      [theme="dark"] & {
        background: $header-background-color-dark;
        border-top-color: $global-border-color-dark;
      }
    }
  }

  &.open {
    .header-wrapper {
      margin-top: -$header-height;
    }

    .menu {
      padding-top: 0;
      border-top: none;

      .menu-item {
        display: none;
      }

      .search-cancel {
        display: inline;
      }
    }
  }
}

.search-dropdown {
  position: fixed;
  z-index: 200;
  top: $header-height;
  @include box-shadow(0 0.125rem 0.25rem rgba(0, 0, 0, 0.1));

  &.desktop {
    right: 2rem;
    width: 30rem;
  }

  &.mobile {
    right: 0;
    width: 100%;
  }

  .dropdown-menu {
    right: 0 !important;
    background-color: $global-background-color;

    [theme="dark"] & {
      background-color: $global-background-color-dark;
    }

    .suggestions {
      overflow-y: auto;
      max-height: calc(100vh - #{$header-height});

      .suggestion {
        padding: 0.75rem 1rem;

        .suggestion-title {
          display: inline-block;
          overflow: hidden;
          text-overflow: ellipsis;
          white-space: nowrap;
          font-size: 1rem;
          font-weight: bold;
          max-width: 75%;
        }

        .suggestion-date {
          font-size: 0.875rem;
          float: right;
          text-align: right;
          color: $global-font-secondary-color;

          [theme="dark"] & {
            color: $global-font-secondary-color-dark;
          }
        }

        .suggestion-context {
          line-height: 1.25rem;
          @include box(vertical);
          -webkit-line-clamp: 2;
          overflow: hidden;
          text-overflow: ellipsis;
          @include overflow-wrap(break-word);
          color: $global-font-secondary-color;

          [theme="dark"] & {
            color: $global-font-secondary-color-dark;
          }
        }

        em {
          font-style: normal;
          background-color: $selection-color;

          [theme="dark"] & {
            background-color: $selection-color-dark;
          }
        }

        &.cursor {
          background: darken($code-background-color, 5%);

          [theme="dark"] & {
            background: lighten($code-background-color-dark, 5%);
          }
        }

        &:hover {
          cursor: pointer;
        }
      }
    }

    .search-empty {
      padding: 1rem;
      text-align: center;

      .search-query {
        font-weight: bold;

        [theme="dark"] & {
          color: #ddd;
        }
      }
    }

    .search-footer {
      padding: 0.5rem 1rem;
      float: right;
      font-size: 0.8rem;
      color: $global-font-secondary-color;

      [theme="dark"] {
        color: $global-font-secondary-color-dark;
      }

      @include link(false, false);

      a {
        font-size: 1rem;
      }
    }
  }
}