/**
 * Variant CSS: nav--transparent-topbar-stacked
 * Layer 2 — two-tier transparent overlay header: a thin top utility strip (secondary
 * quick-links) over the main row (brand + menu + CTA), divided by a hairline. Light
 * on-dark text, no bar fill. Two modes: isolated (relative + dark-band fallback) and
 * overlay (.aibt-header-overlay → floats absolute on the hero). Scope: every selector
 * starts with body.aibt-universal .universal-nav--transparent-topbar-stacked
 */

body.aibt-universal .universal-nav--transparent-topbar-stacked {
	position: relative;
	z-index: 100;
	background: transparent;
	border-bottom: 1px solid rgba(255, 255, 255, 0.18);
	padding-block: 0 !important;
	margin-block: 0 !important;
	background-image: linear-gradient(
		180deg,
		var(--background-dark) 0%,
		color-mix(in oklab, var(--background-dark) 82%, transparent) 100%
	);
}

/* Stacked column: utility strip on top, main row below — shared gutter + cap */
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__inner--stacked {
	display: flex;
	flex-direction: column;
	width: 100%;
	max-width: var(--max-ultra);
	margin-inline: auto;
	padding-inline: clamp(var(--space-md), 4vw, var(--space-xl));
}

/* ── Tier 1: thin utility strip ── */
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__topbar {
	display: flex;
	justify-content: flex-end;
	padding-block: 0.5rem;
	border-bottom: 1px solid rgba(255, 255, 255, 0.14);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__utility {
	font-family: var(--font-body) !important;
	font-size: var(--text-xs) !important;
	color: var(--text-on-dark, #ffffff) !important;
	opacity: 0.72;
	margin: 0 !important;
	letter-spacing: var(--tracking-wide) !important;
	white-space: nowrap;
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__utility a {
	color: inherit;
	text-decoration: none;
	transition: color var(--duration-fast) var(--ease-default), opacity var(--duration-fast) var(--ease-default);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__utility a:hover {
	color: var(--accent);
}

/* ── Tier 2: main row ── */
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__row {
	display: flex;
	align-items: center;
	justify-content: space-between;
	gap: var(--space-md);
	padding-block: 0.95rem;
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__brand {
	font-family: var(--font-display) !important;
	font-weight: 500 !important;
	font-size: 1.4rem !important;
	letter-spacing: -0.01em !important;
	color: var(--text-on-dark, #ffffff) !important;
	margin: 0 !important;
	line-height: 1 !important;
	white-space: nowrap;
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu-wrap {
	display: flex;
	align-items: center;
	gap: var(--space-lg);
	justify-content: flex-end;
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu {
	font-family: var(--font-body) !important;
	font-size: var(--text-sm) !important;
	color: var(--text-on-dark, #ffffff) !important;
	opacity: 0.85;
	margin: 0 !important;
	letter-spacing: 0.02em !important;
	white-space: nowrap;
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu a {
	color: inherit;
	text-decoration: none;
	transition: color var(--duration-fast) var(--ease-default);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu a:hover {
	color: var(--accent);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__cta {
	font-family: var(--font-body);
	font-size: 0.86rem;
	font-weight: 500;
	letter-spacing: var(--tracking-wide);
	padding: 0.62rem 1.4rem;
	color: var(--text-on-dark, #ffffff);
	background: transparent;
	border: 1px solid rgba(255, 255, 255, 0.55);
	text-decoration: none;
	transition: background var(--duration-fast) var(--ease-default),
		border-color var(--duration-fast) var(--ease-default),
		color var(--duration-fast) var(--ease-default);
	min-height: 40px;
	display: inline-flex;
	align-items: center;
	white-space: nowrap;
	border-radius: var(--decor-radius);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__cta:hover {
	background: var(--accent);
	border-color: var(--accent);
	color: var(--cta-text-primary);
}

/* Hamburger toggle (hidden on desktop) — light bars */
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle {
	display: none;
	background: transparent;
	border: 1px solid rgba(255, 255, 255, 0.4);
	cursor: pointer;
	width: 44px;
	height: 44px;
	flex-direction: column;
	align-items: center;
	justify-content: center;
	gap: 6px;
	padding: 0;
	transition: border-color var(--duration-fast) var(--ease-default);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle:hover {
	border-color: var(--text-on-dark, #ffffff);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle-bar {
	display: block;
	width: 18px;
	height: 1.5px;
	background: var(--text-on-dark, #ffffff);
	transition: transform 280ms var(--ease-default);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle[aria-expanded="true"] .universal-nav__toggle-bar:nth-child(1) {
	transform: translateY(4px) rotate(45deg);
}

body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle[aria-expanded="true"] .universal-nav__toggle-bar:nth-child(2) {
	transform: translateY(-3px) rotate(-45deg);
}

/* Keyboard focus rings (a11y) */
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__utility a:focus-visible,
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu a:focus-visible,
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__cta:focus-visible,
body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle:focus-visible {
	outline: 2px solid var(--text-on-dark, #ffffff);
	outline-offset: 3px;
	border-radius: var(--decor-radius);
}

/* ── Mobile: hide the utility strip, collapse the main menu to a dark drop panel ── */
@media (max-width: 781px) {
	body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__topbar {
		display: none;
	}

	body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__toggle {
		display: flex;
	}

	body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu-wrap {
		position: fixed;
		top: 64px;
		left: 0;
		right: 0;
		bottom: 0;
		background: var(--background-dark);
		flex-direction: column;
		gap: 2.5rem;
		justify-content: flex-start;
		align-items: center;
		padding: 3rem 1.5rem 2rem;
		transform: translateY(-110%);
		transition: transform 320ms var(--ease-default);
		z-index: 99;
	}

	body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu-wrap[data-open="true"] {
		transform: translateY(0);
	}

	body.aibt-universal .universal-nav--transparent-topbar-stacked .universal-nav__menu {
		font-size: 1.35rem !important;
		text-align: center;
		white-space: normal;
		opacity: 1;
		line-height: 2;
	}
}

/* ── Overlay mode (transparent-header architecture) — deeper scrim for two tiers ── */
body.aibt-universal .aibt-header-overlay {
	position: relative;
}

body.aibt-universal .aibt-header-overlay .universal-nav--transparent-topbar-stacked {
	position: absolute;
	inset: 0 0 auto 0;
	z-index: 50;
	background: transparent;
	background-image: linear-gradient(
		180deg,
		rgba(0, 0, 0, 0.5) 0%,
		rgba(0, 0, 0, 0.24) 62%,
		rgba(0, 0, 0, 0) 100%
	);
	text-shadow: 0 1px 3px rgba(0, 0, 0, 0.55);
}

body.aibt-universal .aibt-header-overlay .universal-hero {
	padding-top: var(--header-h, 4.75rem);
}

body.aibt-universal .aibt-header-overlay .universal-hero[class*="universal-hero--cover-"] {
	padding-top: 0;
}