skins/Vector/resources/skins.vector.styles/components/MenuTabs.less
/**
 * Styling for namespace tabs (page, discussion) and views (read, edit, view history, watch and other actions)
 */

/* Tab list items */
.vector-menu-tabs {
	float: left;

	// With mw-ui-icons, expand watchstar and wikilove links it to cover full touch area
	.mw-list-item {
		.cdx-button--icon-only {
			// Align small icons with the bottom of the tabs.
			margin: 2px 0 0;
		}
	}

	/* focus and hover have outlines. Text underline interferes with bottom border */
	.mw-list-item.vector-tab-noicon a:focus,
	.mw-list-item.vector-tab-noicon a:hover {
		text-decoration: none;
		border-bottom: 2px @border-style-base;
	}

	/* T361841 add invisible bottom border by default */
	.mw-list-item.vector-tab-noicon a {
		border-bottom: 2px @border-style-base @border-color-transparent;
	}

	// T316574 Override visited link styles
	.mw-list-item a {
		.mixin-vector-unvisited-link-base();
	}

	// Override visited red link styles
	.mw-list-item.new a {
		.mixin-vector-unvisited-link-red();
	}

	.mw-list-item.selected a {
		.mixin-vector-selected-link();
		border-bottom: 2px @border-style-base;
	}
}

/**
 * Tab list item appearance. Applies to both <li>'s inside .vector-menu-tabs
 * and dropdown menus inside the article toolbar
 */
.vector-menu-tabs .mw-list-item.vector-tab-noicon,
.vector-page-toolbar-container .vector-dropdown {
	margin: 0 @padding-horizontal-tabs;
}

.vector-menu-tabs .mw-list-item,
.vector-page-toolbar-container .vector-dropdown-label {
	// Only apply no wrap
	white-space: nowrap;
}

.vector-menu-tabs .mw-list-item,
.vector-page-toolbar-container .vector-dropdown {
	float: left;
	margin-bottom: 0; /* overrides default `li` styling */

	// target links inside of .vector-tab-menu
	// and dropdown toggles inside the article toolbar.
	// NOTE: Consider adding a single selector to define both items,
	// since they both appear beside each other in the article toolbar.
	& > a,
	.vector-dropdown-label {
		display: inline-flex;
		position: relative;
		cursor: pointer;
		font-weight: normal;
	}

	.vector-dropdown-label {
		// For better compatibility with gadgets (like Twinkle) that append
		// <H3> elements as dropdown headings (which was the convention in legacy Vector).
		font-size: inherit;
		// Override button styles on dropdown toggle button
		border: 0;
	}

	&.vector-tab-noicon > a,
	.vector-dropdown-label {
		// Top & bottom padding to increase clickable area.
		padding: @padding-vertical-tabs;
		// bottom margin to overlap border with toolbar border.
		margin-bottom: -1px;
	}
}
