單純BUTTON或用JQUERY跑button()或用DIV自製.....
上層容器的CSS設text-align:center;
<div style="text-align:center;">
<button>1</button>
<button>2</button>
<button>3</button><br>
<button>4</button>
<button>5</button>
<button>6</button>
</div>