<!-- Application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="android:buttonStyle">@style/button_style</item>
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

<style name="button_style" parent="Widget.AppCompat.Button">
    <item name="android:backgroundTint">@color/white_blue</item>
    <item name="android:textColor">@android:color/white</item>
</style>

<Button
    android:id="@+id/b_splash_screen_start"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/start"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.5"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/appCompatTextView"/>

import android.support.v4.app.Fragment;

import android.support.v7.app.AppCompatActivity;