packages/SystemUI/res/drawable/contrast_dialog_button_background.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
/*
* Copyright 2023, The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
-->
<selector
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:androidprv="http://schemas.android.com/apk/prv/res/android">

    <item android:state_selected="true">
        <shape android:shape="rectangle">
            <solid android:color="?androidprv:attr/colorSurfaceHighlight" />
            <stroke
                android:color="?androidprv:attr/colorAccentPrimary"
                android:width="@dimen/contrast_dialog_button_stroke_width" />
            <corners android:radius="@dimen/contrast_dialog_button_radius"/>
        </shape>
    </item>

    <item>
        <layer-list>
            <item android:top="@dimen/contrast_dialog_button_stroke_width"
                android:bottom="@dimen/contrast_dialog_button_stroke_width"
                android:left="@dimen/contrast_dialog_button_stroke_width"
                android:right="@dimen/contrast_dialog_button_stroke_width">
                <shape android:shape="rectangle">
                    <solid android:color="?androidprv:attr/colorSurfaceHighlight" />
                    <corners android:radius="@dimen/contrast_dialog_button_radius"/>
                </shape>
            </item>
        </layer-list>
    </item>
</selector>