/* ══════════════════════════════════════════════════════════════
   Zhanchao Yang — Research study page: Telework & Daily Travel
   Extends home.css. Distinct from the rest of the site: a dark
   "journal" masthead, a terracotta data accent, and an hour-ruler
   motif that carries the argument down the page.
══════════════════════════════════════════════════════════════ */

body.study {
	background: var(--bg);
	color: var(--ink);
	font-family: var(--sans);
	font-size: 16px;
	line-height: 1.65;
	-webkit-font-smoothing: antialiased;
	overflow-x: hidden;

	--accent: #c05a3e;
	--accent-bright: #e07a5f;
	--accent-soft: rgba(215, 106, 84, 0.16);
	--ink-deep: #081c34;
	--on-dark: rgba(255, 255, 255, 0.9);
	--on-dark-soft: rgba(255, 255, 255, 0.62);
	--on-dark-faint: rgba(255, 255, 255, 0.4);
	--dark-line: rgba(255, 255, 255, 0.14);
}

/* the page is meant to be readable in two or three minutes:
   sections sit tighter than the rest of the site */
.study .section {
	padding: 84px 0;
}
.study .section-label {
	color: var(--accent);
}
.study .section-label::before {
	background: var(--accent);
}

/* ── Navigation: ink-dark for the whole study page ─────────── */
.study .site-nav {
	background: rgba(8, 28, 52, 0.9);
	border-bottom: 1px solid transparent;
}
.study .site-nav.scrolled {
	border-bottom-color: rgba(255, 255, 255, 0.12);
}
.study .nav-name {
	color: #fff;
}
.study .nav-affil {
	color: var(--on-dark-faint);
	border-left-color: var(--dark-line);
}
.study .nav-links a {
	color: var(--on-dark-soft);
}
.study .nav-links a:hover,
.study .nav-links a.active {
	color: #fff;
}
.study .nav-links a::after {
	background: var(--accent-bright);
}
.study .nav-toggle span {
	background: #fff;
}

/* ══ Masthead ══════════════════════════════════════════════ */
.st-hero {
	position: relative;
	background: linear-gradient(158deg, #0e2a4c 0%, #081c34 52%, #0c2340 100%);
	color: var(--on-dark);
	padding: 148px 0 0;
	overflow: hidden;
}
/* faint plotting grid behind the masthead */
.st-hero::before {
	content: '';
	position: absolute;
	inset: 0;
	background-image: linear-gradient(rgba(255, 255, 255, 0.04) 1px, transparent 1px),
		linear-gradient(90deg, rgba(255, 255, 255, 0.04) 1px, transparent 1px);
	background-size: 46px 46px;
	-webkit-mask-image: radial-gradient(ellipse 80% 70% at 60% 30%, #000 10%, transparent 78%);
	mask-image: radial-gradient(ellipse 80% 70% at 60% 30%, #000 10%, transparent 78%);
	pointer-events: none;
}
.st-hero > .container {
	position: relative;
	z-index: 2;
}

.st-crumb {
	display: inline-flex;
	align-items: center;
	gap: 10px;
	font-size: 0.78rem;
	font-weight: 500;
	letter-spacing: 0.06em;
	color: var(--on-dark-faint);
	text-decoration: none;
	margin-bottom: 30px;
	transition: color 0.25s ease;
}
.st-crumb .arrow {
	transition: transform 0.3s ease;
}
.st-crumb:hover {
	color: var(--accent-bright);
}
.st-crumb:hover .arrow {
	transform: translateX(-3px);
}

.st-hero-grid {
	display: grid;
	grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
	gap: 56px;
	align-items: center;
	padding-bottom: 56px;
}

.st-eyebrow {
	display: flex;
	align-items: center;
	gap: 12px;
	flex-wrap: wrap;
	font-size: 0.75rem;
	font-weight: 600;
	letter-spacing: 0.18em;
	text-transform: uppercase;
	color: var(--accent-bright);
	margin-bottom: 22px;
}
.st-eyebrow::before {
	content: '';
	width: 30px;
	height: 1.5px;
	background: var(--accent-bright);
}
.st-status {
	color: var(--on-dark);
	background: rgba(255, 255, 255, 0.1);
	border: 1px solid var(--dark-line);
	border-radius: 100px;
	padding: 4px 13px;
	letter-spacing: 0.11em;
}

.st-hero h1 {
	font-family: var(--serif);
	font-size: clamp(2.5rem, 5vw, 3.7rem);
	font-weight: 600;
	line-height: 1.06;
	letter-spacing: -0.018em;
	color: #fff;
	margin-bottom: 22px;
}
.st-hero h1 em {
	font-style: italic;
	color: var(--accent-bright);
}
.st-dek {
	font-family: var(--serif);
	font-size: clamp(1.1rem, 1.9vw, 1.28rem);
	line-height: 1.6;
	color: var(--on-dark-soft);
	max-width: 500px;
	margin-bottom: 26px;
}
.st-lede {
	font-size: 0.96rem;
	line-height: 1.72;
	color: var(--on-dark-soft);
	max-width: 500px;
	margin-bottom: 30px;
}
.st-keywords {
	display: flex;
	flex-wrap: wrap;
	gap: 8px;
}
.st-keywords span {
	font-size: 0.72rem;
	font-weight: 500;
	letter-spacing: 0.04em;
	color: var(--on-dark-soft);
	border: 1px solid var(--dark-line);
	border-radius: 100px;
	padding: 5px 14px;
}

/* headline figure sitting in the masthead */
.st-hero-fig {
	position: relative;
}
.st-hero-fig svg {
	width: 100%;
	height: auto;
	display: block;
	overflow: visible;
}
.st-hero-cap {
	font-size: 0.76rem;
	line-height: 1.6;
	color: var(--on-dark-faint);
	margin-top: 14px;
	max-width: 460px;
}

/* fact rail across the base of the masthead */
.st-facts {
	position: relative;
	z-index: 2;
	border-top: 1px solid var(--dark-line);
	background: rgba(0, 0, 0, 0.16);
}
.st-facts .container {
	display: grid;
	grid-template-columns: repeat(4, 1fr);
	gap: 28px;
	padding-top: 30px;
	padding-bottom: 30px;
}
.st-fact .st-fact-num {
	font-family: var(--serif);
	font-size: 1.62rem;
	font-weight: 600;
	color: #fff;
	line-height: 1.15;
	display: block;
}
.st-fact .st-fact-lab {
	font-size: 0.72rem;
	letter-spacing: 0.12em;
	text-transform: uppercase;
	color: var(--on-dark-faint);
	margin-top: 6px;
	display: block;
}

/* peer-review notice */
.st-notice {
	background: var(--surface-warm);
	border-bottom: 1px solid var(--line-soft);
}
.st-notice .container {
	display: flex;
	align-items: flex-start;
	gap: 16px;
	padding-top: 18px;
	padding-bottom: 18px;
}
.st-notice svg {
	width: 19px;
	height: 19px;
	flex-shrink: 0;
	margin-top: 2px;
	fill: none;
	stroke: var(--accent);
	stroke-width: 1.6;
	stroke-linecap: round;
	stroke-linejoin: round;
}
.st-notice p {
	font-size: 0.86rem;
	color: var(--ink-soft);
	max-width: 860px;
}
.st-notice strong {
	color: var(--ink);
	font-weight: 600;
}

/* ══ Numbered section heads ════════════════════════════════ */
.st-head {
	display: flex;
	align-items: flex-start;
	gap: 26px;
	margin-bottom: 26px;
}
.st-num {
	font-family: var(--serif);
	font-size: 2.7rem;
	font-weight: 600;
	line-height: 1;
	color: var(--sand-deep);
	flex-shrink: 0;
	padding-top: 2px;
	letter-spacing: -0.02em;
}
.st-head .section-title {
	margin-bottom: 0;
}
.st-head .section-label {
	margin-bottom: 12px;
}
.st-body {
	max-width: 700px;
	margin-left: 76px;
}
.st-body p {
	color: var(--ink-soft);
	margin-bottom: 18px;
}
.st-body p:last-child {
	margin-bottom: 0;
}
.st-body strong {
	color: var(--ink);
	font-weight: 600;
}

/* ══ 01 · measurement comparison ═══════════════════════════ */
.section-question {
	background: linear-gradient(180deg, var(--bg) 0%, var(--surface-warm) 100%);
}
.st-compare {
	display: grid;
	grid-template-columns: 1fr 1fr;
	gap: 26px;
	margin-top: 40px;
}
.st-panel {
	background: var(--surface);
	border: 1px solid var(--line-soft);
	border-top: 3px solid var(--blue-soft);
	border-radius: 4px;
	padding: 28px 28px 24px;
	box-shadow: var(--shadow);
}
.st-panel.is-ours {
	border-top-color: var(--accent);
}
.st-panel-kicker {
	font-size: 0.72rem;
	font-weight: 600;
	letter-spacing: 0.15em;
	text-transform: uppercase;
	color: var(--ink-faint);
	margin-bottom: 8px;
}
.st-panel.is-ours .st-panel-kicker {
	color: var(--accent);
}
.st-panel h3 {
	font-family: var(--serif);
	font-size: 1.24rem;
	font-weight: 600;
	margin-bottom: 16px;
	line-height: 1.3;
}
.st-panel-fig {
	margin: 6px 0 16px;
}
.st-panel-fig svg {
	width: 100%;
	max-width: 460px;
	height: auto;
	display: block;
	margin: 0 auto;
}
.st-panel p {
	font-size: 0.92rem;
	color: var(--ink-soft);
}

/* ══ 02 · method rail ══════════════════════════════════════ */
.st-steps {
	list-style: none;
	margin: 40px 0 0;
	position: relative;
	padding-left: 34px;
}
.st-steps::before {
	content: '';
	position: absolute;
	left: 5px;
	top: 8px;
	bottom: 8px;
	width: 1.5px;
	background: linear-gradient(180deg, var(--accent) 0%, var(--sand-deep) 100%);
	opacity: 0.55;
}
.st-step {
	position: relative;
	padding: 0 0 34px;
}
.st-step:last-child {
	padding-bottom: 0;
}
.st-step::before {
	content: '';
	position: absolute;
	left: -34px;
	top: 7px;
	width: 11px;
	height: 11px;
	border-radius: 50%;
	background: var(--bg);
	border: 2px solid var(--accent);
}
.st-step-lab {
	font-size: 0.72rem;
	font-weight: 600;
	letter-spacing: 0.15em;
	text-transform: uppercase;
	color: var(--ink-faint);
	margin-bottom: 5px;
}
.st-step h3 {
	font-family: var(--serif);
	font-size: 1.16rem;
	font-weight: 600;
	margin-bottom: 6px;
}
.st-step p {
	font-size: 0.95rem;
	color: var(--ink-soft);
	max-width: 620px;
}

/* ══ 03 · findings ═════════════════════════════════════════ */
.section-results {
	background: var(--surface-warm);
}
.st-finding {
	display: grid;
	grid-template-columns: minmax(0, 0.86fr) minmax(0, 1.14fr);
	gap: 48px;
	align-items: center;
	padding: 44px 0;
	border-top: 1px solid var(--line-soft);
}
.st-finding:first-of-type {
	border-top: none;
}
/* alternating rows: the figure keeps the wider column either way */
.st-finding.is-flipped {
	grid-template-columns: minmax(0, 1.14fr) minmax(0, 0.86fr);
}
.st-finding.is-flipped .st-finding-text {
	order: 2;
}
.st-find-tag {
	display: inline-flex;
	align-items: center;
	gap: 9px;
	font-size: 0.72rem;
	font-weight: 600;
	letter-spacing: 0.15em;
	text-transform: uppercase;
	color: var(--accent);
	margin-bottom: 14px;
}
.st-find-tag::before {
	content: '';
	width: 7px;
	height: 7px;
	background: var(--accent);
	transform: rotate(45deg);
}
.st-finding h3 {
	font-family: var(--serif);
	font-size: clamp(1.4rem, 2.4vw, 1.75rem);
	font-weight: 600;
	line-height: 1.24;
	margin-bottom: 14px;
}
.st-finding p {
	color: var(--ink-soft);
	margin-bottom: 14px;
}
.st-finding p:last-child {
	margin-bottom: 0;
}
.st-finding strong {
	color: var(--ink);
	font-weight: 600;
}

.st-card {
	background: var(--surface);
	border: 1px solid var(--line-soft);
	border-radius: 4px;
	padding: 24px 26px 18px;
	box-shadow: var(--shadow);
}
.st-card-title {
	font-size: 0.74rem;
	font-weight: 600;
	letter-spacing: 0.14em;
	text-transform: uppercase;
	color: var(--ink-faint);
	margin-bottom: 16px;
}
.st-card svg {
	width: 100%;
	height: auto;
	display: block;
	overflow: visible;
}
.st-card-pair {
	display: grid;
	grid-template-columns: 1fr 1fr;
	gap: 22px;
}
.fig-note {
	font-size: 0.75rem;
	color: var(--ink-faint);
	margin-top: 14px;
	line-height: 1.55;
}

/* pull quote between findings */
.st-quote {
	margin: 8px 0 0;
	padding: 46px 0 4px;
	border-top: 1px solid var(--line-soft);
	text-align: center;
}
.st-quote blockquote {
	font-family: var(--serif);
	font-size: clamp(1.4rem, 2.9vw, 2rem);
	font-weight: 600;
	line-height: 1.32;
	letter-spacing: -0.01em;
	max-width: 780px;
	margin: 0 auto;
}
.st-quote blockquote em {
	font-style: italic;
	color: var(--accent);
}


/* ══ 04 · implications ═════════════════════════════════════ */
.st-implications {
	display: grid;
	grid-template-columns: repeat(3, 1fr);
	gap: 22px;
	margin-top: 40px;
}
.st-imp {
	background: var(--surface);
	border: 1px solid var(--line-soft);
	border-left: 3px solid var(--imp-c, var(--sand-deep));
	border-radius: 3px;
	padding: 26px 26px 24px;
}
.st-imp .icon-badge {
	width: 44px;
	height: 44px;
	margin-bottom: 16px;
}
.st-imp .icon-badge svg {
	width: 21px;
	height: 21px;
}
.st-imp h3 {
	font-family: var(--serif);
	font-size: 1.14rem;
	font-weight: 600;
	margin-bottom: 8px;
	line-height: 1.3;
}
.st-imp p {
	font-size: 0.93rem;
	color: var(--ink-soft);
}
.st-imp-survey { --imp-c: var(--accent); }
.st-imp-models { --imp-c: var(--blue-soft); }
.st-imp-peak { --imp-c: var(--sand-deep); }
.st-imp-equity { --imp-c: var(--sage-deep); }

.st-caveat {
	margin-top: 40px;
	font-size: 0.88rem;
	color: var(--ink-faint);
	max-width: 760px;
	line-height: 1.7;
	border-top: 1px solid var(--line-soft);
	padding-top: 22px;
}

/* ══ Closing ═══════════════════════════════════════════════ */
.section-closing-study {
	background: var(--ink-deep);
	color: var(--on-dark);
	padding: 84px 0;
}
.st-closing {
	max-width: 720px;
}
.st-closing .st-eyebrow {
	margin-bottom: 18px;
}
.st-closing h2 {
	font-family: var(--serif);
	font-size: clamp(1.6rem, 3vw, 2.1rem);
	font-weight: 600;
	line-height: 1.28;
	color: #fff;
	margin-bottom: 16px;
}
.st-closing p {
	color: var(--on-dark-soft);
	margin-bottom: 30px;
}
.st-closing-actions {
	display: flex;
	align-items: center;
	gap: 26px;
	flex-wrap: wrap;
}
.st-closing .btn-primary {
	background: var(--accent-bright);
	border-color: var(--accent-bright);
	color: #0b2345;
}
.st-closing .btn-primary:hover {
	background: #fff;
	border-color: #fff;
	color: var(--ink);
}
.st-text-link {
	font-size: 0.9rem;
	font-weight: 600;
	color: var(--on-dark);
	text-decoration: none;
	display: inline-flex;
	align-items: center;
	gap: 8px;
	border-bottom: 1px solid var(--dark-line);
	padding-bottom: 4px;
	transition: color 0.25s ease, border-color 0.25s ease;
}
.st-text-link:hover {
	color: var(--accent-bright);
	border-color: var(--accent-bright);
}
.st-text-link .arrow {
	transition: transform 0.3s ease;
}
.st-text-link:hover .arrow {
	transform: translateX(4px);
}

/* ══ Figure animation ══════════════════════════════════════ */
.fig-draw {
	stroke-dasharray: 1800;
	stroke-dashoffset: 1800;
	transition: stroke-dashoffset 2.1s cubic-bezier(0.22, 0.61, 0.36, 1) 0.25s;
}
.reveal.in-view .fig-draw,
.st-hero-fig.in-view .fig-draw {
	stroke-dashoffset: 0;
}
.fig-soft {
	opacity: 0;
	transition: opacity 0.9s ease 1.5s;
}
.reveal.in-view .fig-soft,
.st-hero-fig.in-view .fig-soft {
	opacity: 1;
}
.fig-bar {
	transform: scaleY(0);
	transform-box: fill-box;
	transform-origin: bottom;
	transition: transform 1s cubic-bezier(0.22, 0.61, 0.36, 1);
}
.reveal.in-view .fig-bar {
	transform: scaleY(1);
}
.fig-bar-2 { transition-delay: 0.16s; }
.fig-bar-3 { transition-delay: 0.32s; }

/* ══ Responsive ════════════════════════════════════════════ */
@media (max-width: 1000px) {
	.st-hero-grid {
		grid-template-columns: 1fr;
		gap: 44px;
	}
	.st-dek,
	.st-lede {
		max-width: 640px;
	}
	.st-facts .container {
		grid-template-columns: repeat(2, 1fr);
		gap: 24px;
	}
	.st-compare,
	.st-implications {
		grid-template-columns: 1fr;
	}
	.st-finding,
	.st-finding.is-flipped {
		grid-template-columns: 1fr;
		gap: 30px;
	}
	.st-finding.is-flipped .st-finding-text {
		order: 0;
	}
}

@media (max-width: 720px) {
	.st-hero {
		padding-top: 118px;
	}
	.st-head {
		gap: 16px;
	}
	.st-num {
		font-size: 2rem;
	}
	.st-body {
		margin-left: 0;
	}
	.st-card-pair {
		grid-template-columns: 1fr;
	}
	.st-panel,
	.st-card {
		padding: 22px 20px 18px;
	}
	.st-notice .container {
		gap: 12px;
	}
	.section-closing-study {
		padding: 64px 0;
	}
}

/* ══ Reduced motion ════════════════════════════════════════ */
@media (prefers-reduced-motion: reduce) {
	.fig-draw {
		stroke-dasharray: none;
		stroke-dashoffset: 0;
		transition: none;
	}
	.fig-soft {
		opacity: 1;
		transition: none;
	}
	.fig-bar {
		transform: none;
		transition: none;
	}
}