- var letters = [ ["A","B","C","D","E"], ["F","G","H","J","K"] ];
- var groups = 8;
- var itemsPerGroup = 10;
- var itemsInLastGroup = 5;

form(action="")
	- for (g = 0; g < groups; ++g) {
		.bubble-group
			- var ipg = g == groups - 1 ? itemsInLastGroup : itemsPerGroup;
			- for (r = 0; r < ipg; ++r) {
				- var n = r + (itemsPerGroup * g) + 1;
				- var l = letters[r % 2];
				strong=n
				- for (b = 0; b < l.length; ++b) {
					input(type="radio",name="_"+n,id="_"+n+l[b])
					label(for="_"+n+l[b]).bubble
						span.bubble-inner=l[b]
				- }
			- }
	- }
	button(type="submit")="Submit"
View Compiled 
*, *:before, *:after {
	border: 0;
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
:root {
	--c: rgb(32,176,144);
	--c2: rgb(26,130,107);
	font-size: 16px;
}
body, button, input {
	font: 1em "Helvetica Neue", Helvetica, sans-serif;
	line-height: 1.5;
}
body {
	color: rgb(32,176,144);
	color: var(--c);
}
input, button {
	-webkit-appearance: none;
	-moz-appearance: none;
	appearance: none;
}
form {
	padding: 0.75em 0.375em;
	outline: 1px solid red;
}
input[type=radio] {
	opacity: 0;
	position: absolute;
	width: 0;
	height: 0;
}
input[type=radio]:checked + .bubble:after {
	width: 100%;
}
button {
	background: var(--c);
	border-radius: 0.375em;
	color: #fff;
	cursor: pointer;
	display: block;
	margin: auto;
	padding: 0.75em 1em;
	width: 100%;
}
button:active {
	background: var(--c2);
}
/* Bubbles */
.bubble-group {
	font-size: 1.4em;
	display: grid;
	grid-template-columns: 1.75em 2.25em 2.25em 2.25em 2.25em 2.25em;
	align-items: center;
	margin: auto;
	width: 13.25em;
}
.bubble-group > strong {
	letter-spacing: 0.05em;
	line-height: 1;
	text-align: right;
}
.bubble-group:nth-of-type(even) {
	border-radius: 0.375em 0 0 0.375em;
	box-shadow: 2px 0 0 inset, 0 2px 0 inset, 0 -2px 0 inset;
}
.bubble-group:last-of-type {
	margin-bottom: 1.5em;
}
.bubble, .bubble-inner {
	display: inline-block;
}
.bubble {
	border-radius: 50%;
	box-shadow: 0 0 0 1px;
	cursor: pointer;
	font-size: 0.875em;
	line-height: 1.25;
	margin: 0.25em 0.5em;
	overflow: hidden;
	position: relative;
	text-align: center;
	height: 1.25em;
	width: 2.25em;
}
.bubble:after {
	background-color: #555;
	content: "";
	display: block;
	position: absolute;
	top: 0;
	left: 0;
	width: 0;
	height: 100%;
	transition: width 0.1s linear;
	z-index: 1;
}
.bubble-inner {
	background-color: #fff;
	font-weight: bold;
}

@media screen and (min-width: 361px) {
	button {
		width: auto;
	}
}
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