discourse/app/assets/stylesheets/common/select-kit/notifications-button.scss

.select-kit {
  &.dropdown-select-box {
    &.notifications-button {
      .select-kit-body {
        max-width: 400px;
        width: 400px;

        @media screen and (max-width: 767px) {
          width: auto;
        }
      }

      .select-kit-row {
        .icons {
          -ms-flex-item-align: start;
          align-self: flex-start;
        }
      }
    }
  }
}