PortableInfobox/styles/PortableInfoboxMonobook.scss

// fix issues with default infobox styles on monobook

.portable-infobox {
	background-color: #f9f9f9;

	figure {
		margin: 0;
	}

	.portable-infobox-header-background {
		background-color: #e5e5e5;
	}
}