cooleshow_android/teacher/src/main/res/drawable/tab_indicator.xml

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

    <item android:gravity="center">
        <shape>

            <size
                android:width="16dp"
                android:height="4dp" />

            <corners android:radius="2dp" />

            <solid android:color="@color/color_2dc7aa" />

        </shape>
    </item>

</layer-list>