discourse/app/assets/stylesheets/common/base/new-user.scss

.new-user-wrapper {
  .user-nav-dropdown-button {
    background: transparent;
  }

  .user-nav-dropdown-submenu {
    background: var(--secondary);
    list-style-type: none;
    margin: 0;

    li a {
      padding: 0.5em 1em;
      color: var(--primary);

      .discourse-no-touch & {
        &:hover {
          background: var(--highlight-medium);
          color: currentColor;
        }
      }

      &.active {
        background: var(--tertiary-low);
        color: currentColor;
      }

      &:first-of-type {
        padding-top: 0.5em;
      }
      &:last-of-type {
        padding-bottom: 0.5em;
      }
    }
  }
}