Hello. Before launching the application, it looks like this: 
Like the height of the buttons are equal. But after starting the application, it looks like this: 
As you can see, the last element leaves the screen border or its height has decreased. As well as the height of the Button-s are no longer equal. Why is this happening? What needs to be done to prevent this from happening? Here is the xml code:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:text="Вопрос" android:gravity="center" android:layout_width="match_parent" android:layout_height="185dp" android:textColor="#fff" android:id="@+id/QuestionText" android:background="#000000" android:textSize="20dp" /> <LinearLayout android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="wrap_content" android:background="#000000" > <Button android:text="Предыдущий" android:layout_width="0dp" android:layout_weight="1" android:layout_height="match_parent" android:textColor="#000" android:background="#fff" /> <Button android:text="Следующий" android:layout_width="0dp" android:layout_weight="1" android:layout_height="match_parent" android:textColor="#000" android:background="#fff" android:id="@+id/nextButton" android:onClick="ShowNextQuestion" /> </LinearLayout> <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="wrap_content" > <Button android:text="Ответ А" android:layout_width="match_parent" android:layout_weight="1" android:layout_height="70dp" android:textColor="#000000" android:onClick="OptionButtonPressed" android:id="@+id/opta" android:background="#fff" /> <Button android:text="Ответ В" android:layout_width="match_parent" android:layout_weight="1" android:layout_height="70dp" android:textColor="#000000" android:background="#fff" android:id="@+id/optb" android:onClick="OptionButtonPressed" /> </LinearLayout> <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="wrap_content"> <Button android:text="Ответ С" android:background="#fff" android:layout_width="match_parent" android:layout_weight="1" android:layout_height="70dp" android:onClick="OptionButtonPressed" android:id="@+id/optc" /> <Button android:text="Ответ D" android:background="#fff" android:layout_width="match_parent" android:layout_weight="1" android:layout_height="70dp" android:textColor="#000000" android:onClick="OptionButtonPressed" android:id="@+id/optd" /> </LinearLayout>