mediawiki-skins-Citizen/resources/skins.citizen.styles/components/StickyHeader.less

#citizen-page-header-sticky-sentinel {
	grid-area: afterHeader; // align right above content
	height: 1px;
	margin-top: -1px;
	visibility: hidden;
	contain: strict;
}

#citizen-page-header-sticky-placeholder {
	grid-area: afterHeader;
}

.ve-activated,
.action-edit {
	// HACK: So sticky header will never trigger in edit action
	#citizen-page-header-sticky-sentinel {
		display: none;
	}
}

.citizen-page-header {
	position: -webkit-sticky;
	position: sticky;

	&::before {
		position: absolute;
		top: 0;
		right: ~'calc( var(--padding-page ) * -1 )';
		left: ~'calc( var(--padding-page ) * -1 )';
		z-index: @z-index-bottom;
		height: 100%;
		content: '';
		background-color: var( --color-surface-0 );
		filter: opacity( 0.9 );
		-webkit-backdrop-filter: saturate( 50% ) blur( 16px );
		backdrop-filter: saturate( 50% ) blur( 16px );
		opacity: 0;
		transition: var( --transition-hover );
		transition-property: opacity;
	}
}

.citizen-page-header--sticky {
	.citizen-page-header {
		top: 0;
		z-index: @z-index-stacking-3;
		flex-wrap: nowrap;
		white-space: nowrap;
		border-bottom: 1px solid var( --border-color-base );

		&::before {
			opacity: 1;
		}

		.mw-indicators {
			display: none;
		}
	}

	.citizen-page-heading {
		position: relative;
		min-width: 0;
	}

	.firstHeading {
		overflow: hidden;
		font-size: var( --font-size-large );
		text-overflow: ellipsis;
	}

	.citizen-jumptotop {
		position: absolute;
		inset: 0 0 0 0;
		margin: ~'calc( var(  --space-xs ) * -1 )';
		border-radius: var( --border-radius-base );

		&:hover {
			background-color: var( --background-color-button-quiet--hover );
		}

		&:active {
			background-color: var( --background-color-button-quiet--active );
		}
	}
}

// Hide sticky header on scroll down on smaller screens
@media ( max-width: @max-width-breakpoint-tablet ) {
	.citizen-page-header {
		.citizen-page-header--sticky & {
			transition: var( --transition-menu );
			transition-property: transform;

			.citizen-page-heading {
				opacity: 1;
				transition: var( --transition-menu );
				transition-delay: var( --transition-delay-menu );
				transition-property: opacity;
			}
		}
	}
}

// Make sticky header more compact if there are less screen estate
@media ( max-height: 800px ) {
	.citizen-page-header--sticky {
		.citizen-page-header {
			padding-top: var( --space-sm );
			padding-bottom: var( --space-sm );
		}

		.firstHeading,
		.mw-page-title-parenthesis {
			font-size: var( --font-size-medium );
		}
	}
}