Accordion menu delay...

[comport9]

Was hoping someone would have some insight into this: I have a pure css accordion style menu using checkboxes, not :target. This allows me to both open and close menus. I have the menu's height set to 100%. This ensures that no matter how much content I have within the menu's, they resize to fill.

Opening a menu works great, however, when closing a menu there is a slight delay. (Half second maybe? Maybe less...). I don't have any delay in my transitions set.

Here's the code, though it's a bit long...

.ac-container{
	width: 95%;
	margin: 10px auto 30px auto;
	text-align: center;
	border-radius: 10px;
}

.ac-container label{
	font-family: Tahoma;
	padding: 5px 20px;
	position: relative;
	z-index: 20;
	display: block;
	height: 30px;
	cursor: pointer;
	color: grey;
	text-shadow: 1px 1px 1px rgba(255,255,255,0.8);
	line-height: 33px;
	font-weight: bold;
	background: #ffffff;
	background: -moz-linear-gradient(top,  #f9b300 0%, #f9b300 1%, #f9dc90 17%);
	background: -moz-linear-gradient(top, #f9dc90 1%, #f9b300 100%);
	background: -webkit-gradient(linear, left top, left bottom, color-stop(1%,#ffffff), color-stop(100%,#eaeaea));
	background: -webkit-linear-gradient(top, #ffffff 1%,#eaeaea 100%);
	background: -o-linear-gradient(top, #ffffff 1%,#eaeaea 100%);
	background: -ms-linear-gradient(top, #ffffff 1%,#eaeaea 100%);
	background: linear-gradient(top, #ffffff 1%,#eaeaea 100%);
	filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffffff', endColorstr='#eaeaea',GradientType=0 );
	box-shadow: 
		0px 0px 0px 1px rgba(155,155,155,0.3), 
		1px 0px 0px 0px rgba(255,255,255,0.9) inset, 
		0px 2px 2px rgba(0,0,0,0.1);
}

.ac-container label:hover{
	background: #f9b300;
}

.ac-container input:checked + label,
.ac-container input:checked + label:hover{
	background: #f9dc90;
	text-shadow: 0px 1px 1px rgba(255,255,255, 0.6);
	box-shadow: 
		0px 0px 0px 1px rgba(155,155,155,0.3), 
		0px 2px 2px rgba(0,0,0,0.1);
}
.ac-container label:hover:after,
.ac-container input:checked + label:hover:after{
	content: '';
	position: absolute;
	width: 24px;
	height: 24px;
	right: 13px;
	top: 7px;
}

.ac-container .ac-cats{
	display: none;
}

.ac-container .ac-subs{
	display: none;
	background: red;
}

.ac-container article{
	background: grey;
	margin-top: -1px;
	overflow: hidden;
	height: 0px;
	position: relative;
	z-index: 10;
	-webkit-transition: height 0.3s ease-in-out;
	-moz-transition: height 0.3s ease-in-out;
	-o-transition: height 0.3s ease-in-out;
	-ms-transition: height 0.3s ease-in-out;
	transition: height 0.3s ease-in-out;
}

.ac-container article p{
	line-height: 30px;
}

.ac-container input:checked ~ article{
	-webkit-transition: height 0.5s ease-in-out;
	-moz-transition: height 0.5s ease-in-out;
	-o-transition: height 0.5s ease-in-out;
	-ms-transition: height 0.5s ease-in-out;
	transition: height 0.5s ease-in-out;
	box-shadow: 0px 0px 0px 1px rgba(155,155,155,0.3);
}

.ac-container input:checked ~ article.ac-small{
	height: 100%;
}

.feeds {
	display: inline-block;
	padding: 10px;
	background: grey;
	color: orange;
}

#submit_button {
	position: relative;
	outline: none;
	background-color: #a5b8da;
	background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #f9b300), color-stop(100%, #f9dc90));
	background-image: -webkit-linear-gradient(top, #f9b300, #f9dc90);
	background-image: -moz-linear-gradient(top, #f9b300, #f9dc90);
	background-image: -ms-linear-gradient(top, #f9b300, #f9dc90);
	background-image: -o-linear-gradient(top, #f9b300, #f9dc90);
	background-image: linear-gradient(top, #f9b300, #f9dc90);
	border: 1px solid #FCA800;
	border-radius: 18px;
	color: gray;
	font: Tahoma;
	padding: 3px 0;
	text-align: center;
	font-weight: bold;
	width: 125px;
	-moz-box-shadow: -1px 1px 3px #000;
	-webkit-box-shadow: -1px 1px 3px #000;
	box-shadow: -1px 1px 3px #000;
	-webkit-transition: all 5s ease 0s;
	transition: all 5s ease 0s;
}

#submit_button:hover {
	background-color: #9badcc;
	background-image: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #FCE167), color-stop(100%, #F7CA59));
	background-image: -webkit-linear-gradient(top, #FCE167, #F7CA59);
	background-image: -moz-linear-gradient(top, #FCE167, #F7CA59);
	background-image: -ms-linear-gradient(top, #FCE167, #F7CA59);
	background-image: -o-linear-gradient(top, #FCE167, #F7CA59);
	background-image: linear-gradient(top, #FCE167, #F7CA59);
	border: 1px solid #FCA800;
	cursor: pointer;
}

#submit_button:active {
	-webkit-box-shadow: inset 0 0 8px 2px #7e8da6, -1px 1px 3px #000;
	box-shadow: inset 0 0 8px 2px #FCE38F, -1px 1px 3px #000;
}

Any help would be much appreciated.

[comport9]

Did some more testing and figured out that it was the transitions that were the problem.

New question: when the height in .ac-container input:checked ~ article.ac-small is a set amount, say 200px, the transitions work as expected. But when I put 100%, as I have done, the transitions don't work at all. Why is this and is there a way around it?