woocommerce/plugins/woocommerce-blocks/assets/js/base/components/quantity-selector/style.scss

@mixin reset-button {
	border: 0;
	padding: 0;
	margin: 0;
	background: none transparent;
	box-shadow: none;

	&:focus {
		box-shadow: inset 0 0 1px 1px currentColor;
		outline: none;
	}
}

.wc-block-components-quantity-selector {
	border-radius: $universal-border-radius;
	// needed so that buttons fill the container.
	box-sizing: content-box;
	display: flex;
	margin: 0 0 0.25em 0;
	position: relative;
	width: 107px;

	&::after {
		border-radius: $universal-border-radius;
		border: 1px solid $universal-border-light;
		bottom: 0;
		content: "";
		left: 0;
		pointer-events: none;
		position: absolute;
		right: 0;
		top: 0;
	}

	// Extra label for specificity needed in the editor.
	input.wc-block-components-quantity-selector__input {
		@include font-size(regular);
		appearance: textfield;
		background: transparent;
		border: 0;
		box-shadow: none;
		color: currentColor;
		flex: 1 1 auto;
		font-weight: 600;
		line-height: 1;
		margin: 0;
		min-width: 40px;
		order: 2;
		padding: 0.4em 0;
		text-align: center;
		vertical-align: middle;

		&:focus {
			box-shadow: inset 0 0 1px 1px currentColor;
			outline: none;
		}
		&:disabled {
			opacity: 0.6;
		}
	}
	input::-webkit-outer-spin-button,
	input::-webkit-inner-spin-button {
		-webkit-appearance: none;
		margin: 0;
	}

	.wc-block-components-quantity-selector__button {
		@include reset-button;
		@include font-size(regular, 0.9em);
		color: currentColor;
		cursor: pointer;
		font-style: normal;
		font-weight: normal;
		min-width: 30px;
		opacity: 0.6;
		text-align: center;
		text-decoration: none;

		&:hover,
		&:focus {
			opacity: 1;
		}
		&:disabled {
			box-shadow: none;
			cursor: default;
			opacity: 0.6;
		}
	}

	> .wc-block-components-quantity-selector__button--minus {
		border-radius: $universal-border-radius 0 0 $universal-border-radius;
		order: 1;
	}

	> .wc-block-components-quantity-selector__button--plus {
		border-radius: 0 $universal-border-radius $universal-border-radius 0;
		order: 3;
	}
}

.theme-twentyseventeen {
	.wc-block-components-quantity-selector .wc-block-components-quantity-selector__button {
		&:hover,
		&:focus {
			background: none transparent;
		}
	}
}