set footer height

In a view, I want to set the footer height and make it higher than the standard height.

I have tried this,

In view(XML format):

<footer class = "page_footer">

<Toolbar>

<Button text="" icon="sap-icon://account" class="button01"/>

<Button text="" icon="sap-icon://action" class="button02"/>

<Button text="" icon="sap-icon://action-settings" class="button03"/>

</Toolbar>

</footer>

In css:

.view01 .page_footer

{

  height: 80px;

}

But it didnt work.

I use id = "page_footer" and # in css but neither can it.

Can anyone give me some ideas?