* { margin: 0; padding: 0; }
html, body { height: 100%; }
body {
	overflow: hidden;
  position: relative;
	background: slategray url(http://theearlcarlson.com/experiments/amTooltip/img/bg.jpg) 50% no-repeat;
}

/* generic styles for button & circular menu */
.ctrl {
	position: absolute;
	top: 75%; left: 50%;
	font: 1.5em/1.13 Verdana, sans-serif;
	transition: .5s;
}

/* generic link styles */
a.ctrl, .ctrl div {
	display: block;
	opacity: .56;
	background: #c9c9c9;
	color: #7a8092;
	text-align: center;
	text-decoration: none;
	text-shadow: 0 -1px dimgrey;
  cursor: pointer;
}
a.ctrl:hover, .ctrl div:hover, a.ctrl:focus { opacity: 1; }
a.ctrl:focus { outline: none; }
.button {
	z-index: 2;
	margin: -.625em;
	width: 1.25em; height: 1.25em;
	border-radius: 50%;
	box-shadow: 0 0 3px 1px white;
}

/* circular menu */
.tip {
	z-index: 1;
	/**outline: dotted 1px white;/**/
	margin: -5em;
	width: 10em; height: 10em;
	transform: scale(.001);
	list-style: none;
	opacity: 0;
}

/* the ends of the menu */
.tip:before, .tip:after {
	position: absolute;
	top: 34.3%;
	width: .5em; height: 14%;
	opacity: .56;
	background: #c9c9c9;
	content: '';
}
.tip:before {
	left: 5.4%;
	border-radius: .25em 0 0 .25em;
	box-shadow: -1px 0 1px dimgrey, inset 1px 0 1px white, inset -1px 0 1px grey, 
				inset 0 1px 1px white, inset 0 -1px 1px white;
	transform: rotate(-75deg);
}
.tip:after {
	right: 5.4%;
	border-radius: 0 .25em .25em 0;
	box-shadow: 1px 0 1px dimgrey, inset -1px 0 1px white, inset 1px 0 1px grey,
				inset 0 1px 1px white, inset 0 -1px 1px white;
	transform: rotate(75deg);
}

/* make the menu appear on click */
.button:focus + .tip {
	transform: scale(1);
	opacity: 1;
}

/* slices of the circular menu */
.slice {
	overflow: hidden;
	position: absolute;
	/**outline: dotted 1px yellow;/**/
	width: 50%; height: 50%;
	transform-origin: 100% 100%;
}

/* 
 * rotate each slice at the right angle = (A/2)° + (k - (n+1)/2)*A°
 * where A is the angle of 1 slice (30° in this case)
 * k is the number of the slice (in {1,2,3,4,5} here)
 * and n is the number of slices (5 in this case)
 * formula works for odd number of slices (n odd)
 * for even number of slices (n even) the rotation angle is (k - n/2)*A°
 * 
 * after rotating, skew on Y by 90°-A°; here A° = the angle for 1 slice = 30° 
 */
.slice:first-child { transform: rotate(-45deg) skewY(60deg); }
.slice:nth-child(2) { transform: rotate(-15deg) skewY(60deg); }
.slice:nth-child(3) { transform: rotate(15deg) skewY(60deg); }
.slice:nth-child(4) { transform: rotate(45deg) skewY(60deg); }
.slice:last-child { transform: rotate(75deg) skewY(60deg); }

/* covers for the inner part of the links so there's no hover trigger between
   star button & menu links; give them a red background to see them */
.slice:after {
	position: absolute;
	top: 32%; left: 32%;
	width: 136%; height: 136%;
	border-radius: 50%;
	/* "unskew" = skew by minus the same angle by which parent was skewed */
	transform: skewY(-60deg);
	content: '';
}

/* menu links */
.slice div {
	width: 200%; height: 200%;
	border-radius: 50%;
	box-shadow: 0 0 3px dimgrey, inset 0 0 4px white;
	/* "unskew" & rotate by -A°/2 */
	transform: skewY(-60deg) rotate(-15deg);
	background: /* lateral separators */
			linear-gradient(75deg, 
		transparent 50%, grey 50%, transparent 54%) no-repeat 36.5% 0,
			linear-gradient(-75deg, 
		transparent 50%, grey 50%, transparent 54%) no-repeat 63.5% 0,
		/* make sure inner part is transparent */
		radial-gradient(rgba(127,127,127,0) 49%, 
					rgba(255,255,255,.7) 51%, #c9c9c9 52%);
	background-size: 15% 15%, 15% 15%, cover;
	line-height: 1.4;
}

/* arrow for middle link */
.slice:nth-child(3) div:after {
	position: absolute;
	top: 13%; left: 50%;
	margin: -.25em;
	width: .5em; height: .5em;
	box-shadow: 2px 2px 2px white;
	transform: rotate(45deg);
	background: linear-gradient(-45deg, #c9c9c9 50%, transparent 50%);
	content: '';
}