src/css/Button.css

.button {
	position: relative;
	font-size: 1rem;
	padding: 0.5em;
	border: none;
	background: none;
	border-radius: 3em;
	margin: 0.1em;
	background-color: var(--lighter-grey);
	cursor: pointer;
	font-family: var(--font-1);
	flex: 1 1 18%;
	min-width: 7em;
	box-shadow: -0.1em 0.1em 0.1em var(--lightest-grey);
	transition: color 0.2s ease, background-color 0.2s ease;
}

.button[disabled] {
	background-color: var(--lightest-grey);
	color: var(--lighter-grey);
}

.button--selected-true {
	background-color: var(--light-grey);
	color: white;
	box-shadow: -0.1em 0.1em 0.1em var(--blue);
}

.button:not([disabled]):hover,
.button:focus {
	outline: none;
	background-color: var(--light-grey);
	color: white;
}

.button::after,
.button::after {
	content: '';
	position: absolute;
	height: 100%;
	width: 100%;
	top: 0;
	left: 0;
	border-radius: 3em;
	box-shadow: -var(--small) var(--small) var(--medium) var(--blue);
	opacity: 0;
	transition: opacity 0.2s ease;
}

.button:hover::after,
.button:focus::after {
	opacity: 1;
}