WordPress 小工具可以重复使用，相同的小工具样式也是相同的，如果想自定义某个前台添加的小工具样式，与其它不同，可以通过查看原代码，找到它的id，比如搜索小工具会看到类似的：

<section id="search-2" class="widget widget_search">

其中search-2就是这个小工具的ID，可以用#search-2定义样式，不过这个后缀的编号并不是固定的，下次添加可能会变，需要再次编辑之前的样式，有些麻烦。

可以通过下面的代码，给现有的小工具统一增加CSS类选项，将代码添加到当前主题函数模板functions.php中即可，效果如图：

代码一

只加一个CSS类选项

function zm_widget_form_extend( $instance, $widget ) {
  if ( !isset($instance['classes']) )
$instance['classes'] = null;
$row = "<p>n";
$row .= "t<label for='widget-{$widget->id_base}-{$widget->number}-classes'>CSS类</label>n";
$row .= "t<input type='text' name='widget-{$widget->id_base}[{$widget->number}][classes]' id='widget-{$widget->id_base}-{$widget->number}-classes' class='widefat' value='{$instance['classes']}'/>n";
$row .= "</p>n";
echo $row;
return $instance;
}
add_filter('widget_form_callback', 'zm_widget_form_extend', 10, 2);
 
function zm_widget_update( $instance, $new_instance ) {
$instance['classes'] = $new_instance['classes'];
return $instance;
}
add_filter( 'widget_update_callback', 'zm_widget_update', 10, 2 );
 
function zm_dynamic_sidebar_params( $params ) {
global $wp_registered_widgets;
$widget_id    = $params[0]['widget_id'];
$widget_obj    = $wp_registered_widgets[$widget_id];
$widget_opt    = get_option($widget_obj['callback'][0]->option_name);
$widget_num    = $widget_obj['params'][0]['number'];
 
if ( isset($widget_opt[$widget_num]['classes']) && !empty($widget_opt[$widget_num]['classes']) )
$params[0]['before_widget'] = preg_replace( '/class="/', "class="{$widget_opt[$widget_num]['classes']} ", $params[0]['before_widget'], 1 );
return $params;
}
add_filter( 'dynamic_sidebar_params', 'zm_dynamic_sidebar_params' );

代码二

添加ID及CSS类下拉选项

function zm_widget_form_extend( $instance, $widget ) {
if ( !isset( $instance['classes'] ) )
$instance['classes'] = null;
 
if ( !isset( $instance['custom_id'] ) )
$instance['custom_id'] = null;
 
$class_prefix = 'widget-'; 
$myclass = array(
'default'  => '默认',
'blue'     => '蓝色',
'yellow'   => '黄色',
'black'    => '黑色',
);
 
$row = "<p>n";
$row .= "t<label for='widget-{$widget->id_base}-{$widget->number}-custom_id'>添加ID</label>n";
$row .= "t<input type='text' name='widget-{$widget->id_base}[{$widget->number}][custom_id]' id='widget-{$widget->id_base}-{$widget->number}-custom_id' class='widefat' value='{$instance['custom_id']}' />n";
$row .= "t<label for='widget-{$widget->id_base}-{$widget->number}-classes'>CSS类</label>n";
$row .= "t<select name='widget-{$widget->id_base}[{$widget->number}][classes]' id='widget-{$widget->id_base}-{$widget->number}-classes' class='widefat'>";
foreach( $myclass as $key => $class ) {
$selected = null;
if( $class_prefix.$key == $instance['classes'] ) $selected = 'selected = "selected"';
$row .= "t<option value='$class_prefix$key' $selected>$class</value>n";
}
$row .= "</select>n";
echo $row;
return $instance;
}
add_filter('widget_form_callback', 'zm_widget_form_extend', 10, 2);
 
function zm_widget_update( $instance, $new_instance ) {
$instance['classes'] = $new_instance['classes'];
$instance['custom_id'] = $new_instance['custom_id'];
return $instance;
}
add_filter( 'widget_update_callback', 'zm_widget_update', 10, 2 );
 
function zm_dynamic_sidebar_params( $params ) {
global $wp_registered_widgets;
$widget_id  = $params[0]['widget_id'];
$widget_obj = $wp_registered_widgets[$widget_id];
$widget_opt = get_option($widget_obj['callback'][0]->option_name);
$widget_num = $widget_obj['params'][0]['number'];
 
if ( isset( $widget_opt[$widget_num]['classes'] ) && !empty( $widget_opt[$widget_num]['classes'] ) )
$params[0]['before_widget'] = preg_replace( '/class="/', "class="{$widget_opt[$widget_num]['classes']} ", $params[0]['before_widget'], 1 );
if ( isset($widget_opt[$widget_num]['custom_id']) && !empty($widget_opt[$widget_num]['custom_id']) )
$params[0]['before_widget'] = preg_replace( '/id=".*?"/', "id="{$widget_opt[$widget_num]['custom_id']}"", $params[0]['before_widget'], 1 );
return $params;
}
add_filter( 'dynamic_sidebar_params', 'zm_dynamic_sidebar_params' );

代码中预设了CSS类名称，可能使用更方便些。

缺点：添加的选项位置在其它小工具选项的上面，需要改进一下。