discourse/app/assets/stylesheets/common/base/sidebar.scss

:root {
  --d-sidebar-width: #{$d-sidebar-width};
  @include breakpoint(large) {
    --d-sidebar-width: #{$d-sidebar-narrow-width};
  }
  --d-sidebar-animation-time: 0.25s;
  --d-sidebar-animation-ease: ease-in-out;
  // 1.25rem gets text left-aligned with the hamburger icon
  --d-sidebar-row-horizontal-padding: 1.25rem;
  // ems so height is variable along with font size
  --d-sidebar-row-height: 2.1em;

  --d-sidebar-background: var(--secondary);
  --d-sidebar-prefix-background: var(
    --primary-low
  ); // example: chat participant count

  --d-sidebar-header-color: var(--primary);
  --d-sidebar-header-icon-color: var(--primary-medium);

  --d-sidebar-link-color: var(--primary-high);
  --d-sidebar-link-icon-color: var(--primary-500);
  --d-sidebar-link-badge-color: var(--primary-700); // example: new count

  --d-sidebar-highlight-background: var(--primary-low);
  --d-sidebar-highlight-color: var(--primary-high);
  --d-sidebar-highlight-prefix-background: var(--primary-300);
  --d-sidebar-highlight-hover-background: var(
    --primary-medium
  ); // example: hovering a button within a highlighted section
  --d-sidebar-highlight-hover-icon: var(
    --primary-very-low
  ); // example: hovering a button within a highlighted section
}

.sidebar-row {
  box-sizing: border-box;
  height: var(--d-sidebar-row-height);
  padding: 0 var(--d-sidebar-row-horizontal-padding);
  align-items: center;
}

.sidebar-wrapper {
  display: flex;
  grid-area: sidebar;
  position: sticky;
  top: var(--header-offset);
  background: var(--d-sidebar-background);

  @include unselectable;

  // 1dvh with fallback for old browsers
  --1dvh: 1vh;
  @supports (height: 1dvh) {
    --1dvh: 1dvh;
  }

  height: calc(
    var(--composer-vh, var(--1dvh)) * 100 - var(--header-offset, 0px)
  );

  align-self: start;
  overflow-y: auto;

  .sidebar-container {
    display: flex;
    flex-direction: column;
    box-sizing: border-box;
    height: 100%;
    width: 100%;
    padding: 0;
    border-right: 1px solid var(--primary-low);
    overflow-x: hidden;
    // allows sidebar to scroll to the bottom when the composer is open
    height: calc(100% - var(--composer-height, 0px));
  }

  .sidebar-sections {
    display: flex;
    flex-direction: column;
    box-sizing: border-box;
    flex: 1;
    padding: 1.35em 0 1em;
    overflow-x: hidden;
    overflow-y: overlay;

    // custom scrollbar styling
    --scrollbarBg: transparent;
    --scrollbarThumbBg: var(--primary-low);
    --scrollbarWidth: 0.5em;

    scrollbar-color: transparent var(--scrollbarBg);
    transition: scrollbar-color 0.25s ease-in-out;
    transition-delay: 0.5s;

    &::-webkit-scrollbar {
      width: var(--scrollbarWidth);
    }

    &::-webkit-scrollbar-thumb {
      background-color: transparent;
      border-radius: calc(var(--scrollbarWidth) / 2);
    }

    &::-webkit-scrollbar-track {
      background-color: transparent;
    }

    &:hover {
      scrollbar-color: var(--scrollbarThumbBg) var(--scrollbarBg);

      &::-webkit-scrollbar-thumb {
        background-color: var(--scrollbarThumbBg);
      }

      transition-delay: 0s;
    }
  }
  .sidebar-footer-wrapper {
    .btn-flat.add-section {
      padding: 0.25em 0.4em;
      &:hover {
        background: var(--d-sidebar-highlight-background);
        svg {
          color: var(--d-sidebar-link-icon-color);
        }
      }
    }
  }
}
.sidebar-section-form-modal {
  .draggable {
    display: flex;
    height: 100%;
    width: 100%;
    justify-content: center;
    align-items: center;
    color: var(--primary-medium);
    align-self: center;
    margin-left: auto;
    margin-right: auto;
    cursor: move;
    -webkit-user-drag: element;
    user-drag: element;
  }
  .dragging {
    opacity: 0.4;
  }
  .modal-inner-container {
    width: var(--modal-max-width);
  }
  form {
    margin-bottom: 0;
  }
  .input-group input {
    width: 100%;
    margin-bottom: 0;
  }
  input.warning {
    border: 1px solid var(--danger);
  }
  .value.warning {
    position: absolute;
  }
  .row-wrapper {
    display: grid;
    grid-template-columns: 2em 4.5em repeat(2, 1fr) 2em;
    padding: 0.55em 0 0.7em;
    -webkit-user-drag: none;
    user-drag: none;
    cursor: default;
    border-top: 2px solid transparent;
    border-bottom: 2px solid transparent;
    margin-bottom: -2px;
    &.header {
      padding-bottom: 0;
      padding-top: 1em;
      label {
        margin-bottom: 0;
      }
    }

    &.drag-above {
      border-top: 2px solid var(--tertiary);
    }
    &.drag-below {
      border-bottom: 2px solid var(--tertiary);
    }
    .link-icon {
      grid-column: 2;
    }
    &.mark-public-wrapper {
      label {
        grid-column: 1 / -1;
      }
    }
    .input-group {
      margin: 0 0.5em;
      @include breakpoint(mobile-large) {
        margin: 0 0.25em;
      }
    }
  }
  .btn-flat.add-link {
    margin-top: 0.5em;
    margin-left: -0.5em;
    &:active,
    &:focus {
      background: none;
    }
    svg {
      color: var(--tertiary);
      width: 0.75em;
      height: 0.75em;
    }
    &:hover svg {
      color: var(--tertiary-hover);
    }
  }
  .modal-footer {
    display: flex;
    justify-content: space-between;

    .delete {
      margin-right: 0;
    }
  }
  .select-kit.multi-select .multi-select-header .formatted-selection {
    display: none;
  }
  .modal-inner-container .select-kit {
    width: 100%;
    height: 100%;
    .select-kit-header {
      height: 100%;
    }
  }
  .select-kit.is-expanded .select-kit-body {
    min-width: 220px;
  }
  .reset-link {
    margin-right: 0;
    .discourse-no-touch & {
      &:hover {
        .d-icon {
          color: var(--tertiary-hover);
        }
      }
    }
    .d-icon {
      font-size: var(--font-down-1);
      color: var(--tertiary);
    }
  }
  .delete-link {
    .d-icon {
      color: var(--primary-medium);
    }
    .discourse-no-touch & {
      &:hover {
        .d-icon {
          color: var(--danger);
        }
      }
    }
  }
}