ionic-framework/ionic/components/button/test/clear/main.html

<ion-toolbar>
  <ion-title>Clear Buttons</ion-title>
</ion-toolbar>

<ion-content padding style="text-align:center">

  <p>
    <button clear>Default</button>
    <button clear class="activated">Default.activated</button>
  </p>

  <p>
    <button clear primary>Primary</button>
    <button clear primary class="activated">Primary.activated</button>
  </p>

  <p>
    <button clear secondary>Secondary</button>
    <button clear secondary class="activated">Secondary.activated</button>
  </p>

  <p>
    <button clear danger>Danger</button>
    <button clear danger class="activated">Danger.activated</button>
  </p>

  <p>
    <button clear light>Light</button>
    <button clear light class="activated">Light.activated</button>
  </p>

  <p>
    <button clear dark>Dark</button>
    <button clear dark class="activated">Dark.activated</button>
  </p>

</ion-content>