codex.docs/src/frontend/styles/components/sidebar.pcss

.docs-sidebar {

  /* Bottom and Left coord of the "Hide Sidebar" toggler  */
  --hide-sidebar-toggler-offset: 11px;
  --hide-sidebar-toggler-size: 28px;

  @media (--widest-desktop) {
    --hide-sidebar-toggler-offset: var(--layout-padding-horizontal);
    --hide-sidebar-toggler-size: 32px;
  }

  &--animated {
    .docs-sidebar__content {
      transition: transform 200ms ease-in-out;
      will-change: transform;
    }

    .docs-sidebar__slider {
      transition: transform 200ms ease-in-out;
      will-change: transform;
    }
  }

  &--collapsed {
    @media (--desktop) {
      .docs-sidebar__content {
        transform: translateX(-100%);
      }
    }

    .docs-sidebar__slider {
      transform: translateX(var(--hide-sidebar-toggler-offset));

      svg {
        transform: rotate(180deg);
      }
    }
  }

  @media (--desktop) {
    width: var(--layout-sidebar-width);
  }

  &__content {
    border-bottom: 1px solid var(--color-line-gray);
    box-sizing: border-box;
    padding: var(--layout-padding-vertical) var(--layout-padding-horizontal);
    position: sticky;
    top: var(--layout-height-header);
    display: flex;
    flex-direction: column;
    overflow: auto;

    @media (--desktop) {
      height: calc(100vh - var(--layout-height-header));
      border-right: 1px solid var(--color-line-gray);
      border-bottom: 0;
      padding-bottom: 0;
    }

    @media (--tablet) {
      display: none;
    }

    @media (--mobile) {
      display: none;
      padding: var(--layout-padding-vertical) 7px;
    }

    &--visible {
      display: block;
    }

    &--invisible {
      visibility: hidden;
    }
  }

  &__search {
    @apply --input;

    appearance: none;
    background: url("../svg/search.svg") left 10px center no-repeat;
    background-color: var(--color-input-primary);
    border: 1px solid transparent;
    border-radius: 8px;
    padding: 7.5px 35px;
    padding-right: 42px;
    line-height: 17px;
    font-size: 14px;

    &-wrapper::after {
      color: var(--color-button-secondary);
      font-weight: 400;
      font-size: 14px;
      line-height: 17px;
      content: attr(data-shortcut);
      margin-left: -45px;
    }

    @media (--mobile) {
      display: none;

      &-wrapper::after {
        content: "";
        margin-left: 0px;
      }
    }
  }

  &__search::placeholder {
    color: var(--color-button-secondary);
    font-weight: 400;
  }

  &__section {
    overflow: hidden;
    flex-shrink: 0;
    margin-top: 20px;

    &--hidden {
      display: none;
    }

    &--animated {
      .docs-sidebar__section-list {
        transition: max-height 200ms ease-in-out;
      }

      .docs-sidebar__section-toggler {
        svg {
          transition: transform 200ms ease-in;
        }
      }
    }

    &--collapsed {
      .docs-sidebar__section-list {
        max-height: 0 !important;
      }

      .docs-sidebar__section-toggler {
        svg {
          transform: rotate(180deg);
        }
      }
    }
  }

  @media (--mobile) {
    &__section:nth-child(2) {
      margin-top: 0px;
    }
  }

  &__section-title {
    font-size: 16px;
    line-height: 24px;
    font-weight: 700;
    z-index: 2;
    position: relative;
    height: 34px;
  }

  &__section-list-item {
    font-size: 14px;
    line-height: 21px;
    height: 29px;

    @media (--mobile) {
      font-size: 16px;
      line-height: 21px;
    }
  }

  &__section-title,
  &__section-list-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 8px;
    transition-property: background-color;
    transition-duration: 0.1s;

    @apply --squircle;

    &--selected {
      border-radius: 8px;
      /* border using box-shadow which doesn't increase the height */
      box-shadow: 0 0 0 2px rgba(147, 166, 233, 0.5) inset;
    }
  }

  &__section-title > span,
  &__section-list-item > span {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  &__section-title-wrapper {
    &:not(:last-child) {
      padding-bottom: 1px;
      display: block;
    }
  }

  &__section-list-item-wrapper {
    padding: 1px 0;
    display: block;
    &--hidden {
      display: none !important;
    }
  }

  li:last-child {
    .docs-sidebar__section-list-item-wrapper {
      padding-bottom: 0;
    }
  }

  &__section-title:not(&__section-title--active),
  &__section-list-item:not(&__section-list-item--active) {
    @media (--can-hover) {
      &:hover {
        background: var(--color-link-hover);
      }
    }
  }

  &__section-title--active,
  &__section-list-item--active {
    background: linear-gradient(270deg, #129bff 0%, #8a53ff 100%);
    color: white;

    @media (--can-hover) {
      .docs-sidebar__section-toggler:hover {
        background: rgba(0, 0, 0, 0.3);
      }
    }
  }

  &__section-list {
    list-style: none;
    padding: 0;
    margin: 0;
    z-index: 1;
    position: relative;
  }

  &__section-toggler {
    color: inherit;
    background: transparent;
    padding: 0;
    border: 0;
    cursor: pointer;
    width: 24px;
    height: 24px;
    transition-property: background-color;
    transition-duration: 0.1s;

    @apply --squircle;

    @media (--can-hover) {
      &:hover {
        background: white;
      }
    }

    svg {
      display: block;
    }
  }

  &__toggler {
    color: var(--color-text-second);
    padding: 20px 15px;
    border-bottom: 1px solid var(--color-line-gray);

    @media (--desktop) {
      display: none;
    }

    svg {
      margin-right: 10px;
    }
  }

  &__slider {
    display: none;
    position: fixed;
    transform: translateX(
      calc(var(--layout-sidebar-width) + var(--hide-sidebar-toggler-offset))
    );
    bottom: var(--hide-sidebar-toggler-offset);
    width: var(--hide-sidebar-toggler-size);
    height: var(--hide-sidebar-toggler-size);
    cursor: pointer;
    background-color: var(--color-link-hover);
    z-index: 10;

    @apply --squircle;

    @media (--desktop) {
      display: flex;
      justify-content: center;
      align-items: center;
    }
  }

  &__logo {
    display: none;
    margin-top: auto;
    background: white;
    z-index: 2;
    padding-bottom: 20px;
    padding-top: 60px;
    font-size: 14px;
    color: var(--color-text-second);

    @media (--desktop) {
      display: block;
    }

    &-image {
      display: inline-flex;
    }

    &-caption {
      margin: 0;
    }

    &-wrapper {
      display: flex;
      align-items: center;
      gap: 18px;
      padding: 8px;
    }
  }
}