Toolbar style in scaffold example

[ghost]

The core-scaffold example code on polymer core-scaffold page

<core-scaffold>
  <core-header-panel navigation flex mode="seamed">
    <core-toolbar>Application</core-toolbar>
    <core-menu theme="core-light-theme">
      <core-item icon="settings" label="item1"></core-item>
      <core-item icon="settings" label="item2"></core-item>
    </core-menu>
  </core-header-panel>
  <div tool>Title</div>
  <div>Main content goes here...</div>
</core-scaffold>

Renders differently on chrome. The "Application" toolbar has no default color, but chrome and safari seem to inherit this style:

The demo page adds style="background-color: #526E9C; color: #fff;" in the core-toolbar tag, which corrects the style.
But why is it necessary to add this element here?