Hello, This is a Dialog Activity. I want to remove the blank space. How can I make it? Unfortunately, I am stuck.Thanks in advance..

This is my styles file

 <style name="ThemeDialog" parent="Theme.AppCompat.Light.Dialog">
    <item name="android:windowActionBar">false</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowFullscreen">false</item>
</style>

This is my Manifest.xml

  <activity
                android:name=".Activities.AboutActivity"
                android:label="@string/hakkinda"
                android:theme="@style/ThemeDialog"
                android:screenOrientation="portrait"/>

This my onCreate method

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_about);

    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(mViewPager);
}

This is my activity_about

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="400dp"
    android:fitsSystemWindows="true"
    tools:context=".Activities.AboutActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top" >

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

</android.support.design.widget.CoordinatorLayout>

Try changing your ThemeDialog style to this:

<style name="ThemeDialog" parent="@style/Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:backgroundDimEnabled">true</item>
</style>

And maybe in your activity root layout your should add a paddingTop and paddingBottom instead of hard coding the height.