Overleaf/services/web/frontend/stylesheets/bootstrap-5/pages/editor/left-menu.scss

:root {
  --left-menu-form-select-border: var(--border-primary);
}

@include theme('light') {
  --left-menu-form-select-border: var(--border-disabled);
}

.left-menu {
  position: absolute;
  top: 0;
  bottom: 0;
  background-color: var(--bg-light-secondary);
  z-index: 100;
  overflow: hidden auto;
  transition: left ease-in-out 0.5s;
  font-size: var(--font-size-02);
  width: 340px;

  &.shown {
    left: 0;
  }

  h4 {
    font-family: $font-family-sans-serif;
    font-weight: 400;
    font-size: var(--font-size-03);
    margin: var(--spacing-05) 0;
    padding-bottom: var(--spacing-03);
    color: var(--content-secondary);
    border-bottom: 1px solid var(--border-primary-dark);

    &:first-child {
      margin-top: 0;
    }
  }

  ul.nav {
    .left-menu-button {
      cursor: pointer;
      padding: var(--spacing-03);
      font-weight: 700;
      color: var(--link-ui);
      display: flex;
      align-items: center;
      width: 100%;
      background-color: inherit;
      border: none;
      text-decoration: none;

      .material-symbols {
        margin-right: var(--spacing-04);
        color: var(--neutral-70);
      }

      &:hover,
      &:active {
        background-color: var(--bg-info-01);
        color: var(--white);

        .material-symbols {
          color: var(--white);
        }
      }
    }

    a {
      cursor: pointer;

      &:hover,
      &:active,
      &:focus {
        background-color: var(--bg-info-01);
        color: var(--white);

        .material-symbols {
          color: var(--white);
        }
      }

      .material-symbols {
        color: var(--neutral-70);
      }

      padding: var(--spacing-03);
      font-weight: 700;
    }

    .link-disabled {
      color: var(--content-disabled);
    }
  }

  > ul.nav:last-child {
    margin-bottom: var(--spacing-05);
  }

  ul.nav-downloads {
    li {
      display: inline-block;
      text-align: center;
      width: 100px;

      a {
        color: var(--content-secondary);
        text-decoration: none;
      }

      .material-symbols {
        margin: var(--spacing-03) 0;
      }
    }
  }

  form.settings {
    label {
      font-weight: normal;
      color: var(--content-secondary);
      flex: 1 0 50%;
      margin-bottom: 0;
      padding-right: var(--spacing-03);
      white-space: nowrap;
    }

    button,
    select {
      width: 50%;
      margin: var(--spacing-04) 0;
    }
  }

  .left-menu-setting-position {
    position: relative;

    .left-menu-setting {
      margin-top: 0 !important;
    }

    .left-menu-setting-icon {
      position: absolute;
      right: 65%;
      top: 25%;
    }
  }

  .left-menu-setting {
    padding: 0 var(--spacing-02);
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    border-bottom: 1px solid rgb(0 0 0 / 7%);
    margin-bottom: 0;
    height: 43px;

    &:first-child {
      margin-top: calc(var(--spacing-04) * -1);
    }

    &:last-child {
      border-bottom: 0;
    }

    &:hover,
    &:focus-within {
      background-color: var(--bg-info-01);

      label {
        color: var(--white);
      }
    }

    .form-select {
      border: 1px solid var(--left-menu-form-select-border);
    }
  }
}

#left-menu-mask {
  opacity: 0.4;
  background-color: #999;
  z-index: 99;
  transition: opacity 0.5s;
  position: absolute;
  inset: 0;
}

.left-menu-modal-backdrop {
  background-color: transparent;
}

.loading-spinner-container {
  display: flex;
  align-items: center;
  justify-content: center;
}

.full-size-loading-spinner-container {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.reference-manager-search-group {
  width: '100%';
  border-radius: 0;
  text-align: left;

  .dropdown-menu {
    width: 100%;
  }
}