style.css

.edit-post-visual-editor {
  .button,
  .plugin-block__button,
  .pluginB_Block--button,
  .plugin_c_button,
  .plugin-d-block-button a {
    // Attempt to reset some global styles that can't be dequeued.
    background: none;
    border: 0;

    @include button();
  }

  // This plugin actually adds an extra <span> tag.
  .plugin-e-block-button span {

    @include button();
  }

  // This plugin applies alignment classes to the wrapper <div>.
  .plugin_c_button {

    .alignwide & {

    }
  }

  // This plugin applies alignment classes to the <a> tag.
  .plugin-block__button.alignwide {

  }
}