woocommerce/plugins/woocommerce-admin/client/header/activity-panel/activity-header/style.scss

.woocommerce-layout__activity-panel-header {
	height: 50px;
	background: $core-grey-light-500;
	padding: 16px;
	display: flex;
	justify-content: space-between;
	align-items: center;

	@include breakpoint( '>782px' ) {
		padding: 16px 24px 16px 24px;
	}

	h3 {
		font-size: 13px;
		font-weight: 600;
		line-height: 16px;
		margin: 0;
		padding: 0;
	}

	.woocommerce-ellipsis-menu__toggle.components-button:not(:disabled):not([aria-disabled='true']):focus,
	.woocommerce-ellipsis-menu__toggle.components-button:not(:disabled):not([aria-disabled='true']):hover {
		box-shadow: none;
		border-radius: 10px;
		background: $core-grey-light-700;
	}
}

.woocommerce-layout__inbox-panel-header {
	padding: 15px 43px 10px;
	h3 {
		margin: 5px 0;
		font-weight: 500;
	}
	span {
		margin-left: 7px;
		background: #40464d;
		border-radius: 0.8em;
		color: $core-grey-light-200;
		display: inline-block;
		text-align: center;
		width: 1.6em;
		font-size: 14px;
		vertical-align: top;
	}
}