使用PreferenceScreen时如何删除边距

Question

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

<SwitchPreference
    android:defaultValue="false"
    android:key="some_key"
    android:title="@string/some_string"
    android:dialogTitle="@string/dialog_string"
    android:persistent="true"
    />

</PreferenceScreen>

如何删除＆＃34;侧边距＆＃34;？