awtk/demos/assets/raw/styles/tab_bottom.xml

<tab_button_group>
  <style name="highlight" border_color="#1296db">
    <normal/>
  </style>
</tab_button_group>

<tab_button>
  <style name="default" margin="4" text_color="black" bg_color="#eeeeee">
    <normal     />
    <pressed    />
    <over       />
  </style>
  <style name="default_active" margin="4" text_color="#00aa00" bg_color="#eeeeee">
    <normal     />
    <pressed    />
    <over       />
  </style>
</tab_button>

<pages>
  <style name="at_top" border_color="#a0a0a0" border="bottom">
    <normal />
  </style>
</pages>