Can't center menu

I can’t get the menu to center on the page:
http://discoveringyourgoddess.com/portfolio-items/spiritual-development/

I have specified the following css style:

.dyg-pink-buttons-short ul{
	text-align:center !important;
	margin:0 auto;
	padding:0px;
	width:900px !important;
}

.dyg-pink-buttons-short li {
       display:inline;
}

.dyg-pink-buttons-short a {
	text-transform:lowercase;
	background-color:#DED8E4;
	background-image: url(/wp-content/uploads/button-blight-purple-linen3.jpg);
	border:1px solid #ECE5F1;
	border-radius:0px;
	padding:12px 8px 12px;
	margin-left:5px;
	margin-right:5px;
	line-height:70px;
	white-space: nowrap;
}

.dyg-pink-buttons-short a {
	color:#4E3D7A !important;
	text-transform:lowercase;
}

.dyg-pink-buttons-short a:hover{
	color:#ffffff !important;
	background-color:#4E3D7A;
	background-image: url(/wp-content/uploads/button-dark-purple-linen2.jpg);
	border:1px solid #9786AE;
	border-radius:0px;
}

.dyg-pink-buttons-short a:hover{
	color:#ffffff !important;
	}

I have tried both:

[shortmenu menu="Spirit Page Buttons" class="dyg-pink-buttons-short"  display="block"  enhance="false" ]

[shortmenu menu="Spirit Page Buttons" class="dyg-pink-buttons-short"  display="inline"  enhance="false" ]

https://wordpress.org/plugins/shortcode-menu/