<label for="form_preis">Preis</label><br>
<input id="form_preis" name="preis" size="10">
<div class="buttons" style="margin-top: 15px;">
-<button onclick="return add_price(this);">Hinzufügen</button>
+<button class="custom" onclick="return add_price(this);">Hinzufügen</button>
</div>
</form>
</div>
$buttons = <<<EOC
<p style="margin-top: 5px; margin-bottom: 4px; text-align: center;">
-<button onclick="return open_popup()">Preis hinzufügen</button>
+<button class="custom" onclick="return open_popup()">Preis hinzufügen</button>
</p>
EOC;