/* The notebook: chrome shared by every page (header, footer, back-to-top, buttons, tokens).
   Loaded by the homepage, About, the 404 and every case study.
   Page-specific looks live in sheet.css (home, About, 404), home.css, about.css and case-skin.css. */

:root {
	--paper: #f5f6f8;
	--paper-2: #ffffff;
	--ink: #0c1222;
	--ink-2: #333b4f;
	--ink-3: #5d6578;
	--rule: rgba(12, 18, 34, 0.12);
	--rule-strong: rgba(12, 18, 34, 0.22);
	--accent: #2646f5;
	--accent-text: #1c37d0;
	--pen: #d8432f;
	--hl: #ffe45c;
	--tape: rgba(255, 228, 92, 0.72);
	--serif: "EB Garamond", "Iowan Old Style", "Palatino Linotype", Palatino, serif;
	--sans: "Figtree", "Helvetica Neue", Helvetica, Arial, sans-serif;
	--mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	--hand: "Caveat", "Segoe Script", cursive;
	--ease: cubic-bezier(0.22, 1, 0.36, 1);
	--pad: clamp(1.25rem, 4vw, 3.5rem);
	--max: 1180px;
	--nav: 4.5rem;
}

*,
*::before,
*::after {
	box-sizing: border-box;
}

:focus-visible {
	outline: 2px solid var(--accent);
	outline-offset: 3px;
}

::selection {
	background: var(--hl);
	color: var(--ink);
}

.mono {
	font-family: var(--mono);
	font-size: 0.72rem;
	letter-spacing: 0.07em;
	text-transform: uppercase;
}

.hand {
	font-family: var(--hand);
	color: var(--pen);
	font-size: 1.5rem;
	line-height: 1.05;
	font-weight: 500;
}

.sr-only {
	position: absolute;
	width: 1px;
	height: 1px;
	overflow: hidden;
	clip: rect(0 0 0 0);
	white-space: nowrap;
}

.skip {
	position: absolute;
	left: 1rem;
	top: -4rem;
	z-index: 60;
	background: var(--ink);
	color: var(--paper);
	padding: 0.6rem 0.9rem;
	border-radius: 6px;
}

.skip:focus {
	top: 1rem;
}

/* ---------- top bar: sticky, slides away while scrolling down, returns on any scroll up ---------- */
[data-header] {
	position: sticky;
	top: 0;
	z-index: 30;
	height: var(--nav);
	background: color-mix(in srgb, var(--paper) 84%, transparent);
	backdrop-filter: blur(14px);
	-webkit-backdrop-filter: blur(14px);
	transition: transform 0.35s var(--ease);
}

[data-header].is-scrolled {
	border-bottom: 1px dashed var(--rule-strong);
}

/* it stays put while it holds keyboard focus (:focus-visible), but not after a mouse click */
[data-header].is-hidden:not(:has(:focus-visible)) {
	transform: translateY(-100%);
}

.nav-inner {
	height: 100%;
	max-width: calc(var(--max) + var(--pad) * 2);
	margin: 0 auto;
	padding: 0 var(--pad);
	display: flex;
	align-items: center;
	justify-content: space-between;
	gap: 1rem;
}

.logo {
	flex-shrink: 0;
	white-space: nowrap;
	font-family: var(--serif);
	font-size: 1.35rem;
	letter-spacing: -0.01em;
	text-decoration: none;
	color: var(--ink);
}

.nav-links {
	display: flex;
	align-items: center;
	gap: 1.4rem;
	font-size: 0.95rem;
}

.nav-links a {
	text-decoration: none;
	color: var(--ink);
}

.nav-links a:not(.nav-cta):hover {
	text-decoration: underline;
	text-decoration-color: var(--pen);
	text-decoration-thickness: 2px;
	text-underline-offset: 5px;
}

/* the page you are on gets the highlighter */
.nav-links a[aria-current="page"]:not(.nav-cta) {
	background: linear-gradient(transparent 58%, var(--hl) 58%, var(--hl) 92%, transparent 92%);
	color: var(--ink);
}

.nav-cta {
	white-space: nowrap;
	padding: 0.5rem 1rem;
	border: 1px solid var(--ink);
	border-radius: 999px;
	background: var(--paper);
	font-weight: 500;
	transition: background 0.2s, color 0.2s, border-color 0.2s;
}

.nav-cta:hover,
.nav-cta:focus-visible {
	background: var(--accent);
	border-color: var(--accent);
	color: #fff;
}

/* ---------- buttons ---------- */
.btn {
	display: inline-block;
	text-decoration: none;
	font-family: var(--sans);
	font-weight: 500;
	font-size: 0.95rem;
	line-height: 1.4;
	padding: 0.65rem 1.05rem;
	border: 1px solid var(--ink);
	border-radius: 999px;
	background: var(--paper);
	color: var(--ink);
	cursor: pointer;
	transition: background 0.2s, color 0.2s, border-color 0.2s;
}

.btn--solid,
.btn--accent {
	background: var(--ink);
	color: var(--paper);
}

.btn--block {
	display: block;
	text-align: center;
}

.btn:hover,
.btn:focus-visible {
	border-color: var(--accent);
	background: var(--accent);
	color: #fff;
}

mark {
	background: linear-gradient(transparent 55%, var(--hl) 55%, var(--hl) 92%, transparent 92%);
	color: inherit;
}

/* ---------- footer ---------- */
[data-footer] {
	padding: 4rem 0 2.2rem;
	border-top: 1px solid var(--ink);
	margin-top: 2rem;
}

.foot-top .foot-mail {
	display: inline-block;
	margin: 0 0 2rem;
	font-family: var(--serif);
	font-size: clamp(2.3rem, 6.6vw, 5.05rem);
	line-height: 0.98;
	letter-spacing: -0.02em;
	text-decoration: none;
	color: var(--ink);
	background: linear-gradient(var(--hl), var(--hl)) no-repeat 0 92% / 0 0.28em;
	transition: background-size 0.5s var(--ease);
}

.foot-mail:hover,
.foot-mail:focus-visible {
	background-size: 100% 0.28em;
}

.foot-meta {
	display: flex;
	flex-wrap: wrap;
	justify-content: space-between;
	gap: 0.8rem 2rem;
	padding-top: 1.2rem;
	border-top: 1px dashed var(--rule-strong);
	color: var(--ink-2);
	font-family: var(--mono);
	font-size: 0.72rem;
	letter-spacing: 0.07em;
	text-transform: uppercase;
}

.foot-meta p {
	margin: 0;
}

.foot-links {
	display: flex;
	flex-wrap: wrap;
	gap: 0.6rem 1.2rem;
}

.foot-links a {
	color: inherit;
	text-decoration: none;
	border-bottom: 1px solid transparent;
}

.foot-links a:hover,
.foot-links a:focus-visible {
	border-bottom-color: var(--pen);
}

/* ---------- back to top (added to every page by site.js) ---------- */
.to-top {
	position: fixed;
	right: 20px;
	bottom: 20px;
	z-index: 30;
	display: flex;
	align-items: center;
	justify-content: center;
	width: 44px;
	height: 44px;
	padding: 0;
	border: 1px solid var(--ink);
	border-radius: 50%;
	background: var(--paper-2);
	color: var(--ink);
	box-shadow: 0 6px 18px rgba(12, 18, 34, 0.14);
	cursor: pointer;
	opacity: 0;
	pointer-events: none;
	transform: translateY(8px);
	transition: opacity 0.3s ease, transform 0.3s var(--ease), color 0.2s ease, border-color 0.2s ease;
}

.to-top.is-shown {
	opacity: 1;
	pointer-events: auto;
	transform: none;
}

.to-top:hover,
.to-top:focus-visible {
	color: var(--pen);
	border-color: var(--pen);
	transform: translateY(-2px);
}

.to-top svg {
	width: 16px;
	height: 16px;
	fill: none;
	stroke: currentColor;
	stroke-width: 1.6;
	stroke-linecap: round;
	stroke-linejoin: round;
}

.to-top-tip {
	position: absolute;
	right: calc(100% + 10px);
	top: 50%;
	padding: 0 6px;
	background: var(--paper-2);
	color: var(--pen);
	font-family: var(--hand);
	font-size: 1.3rem;
	line-height: 1.2;
	white-space: nowrap;
	opacity: 0;
	pointer-events: none;
	transform: translate(4px, -50%) rotate(-3deg);
	transition: opacity 0.2s ease, transform 0.2s ease;
}

@media (hover: hover) {
	.to-top:hover .to-top-tip {
		opacity: 1;
		transform: translate(0, -50%) rotate(-3deg);
	}
}

.to-top:focus-visible .to-top-tip {
	opacity: 1;
	transform: translate(0, -50%) rotate(-3deg);
}

/* ---------- "password-protected" hints go away once someone has unlocked (site.js sets .is-unlocked) ---------- */
.unlock-only {
	display: none;
}

.is-unlocked .unlock-only {
	display: inline-block;
}

.is-unlocked [data-lock-ui] {
	display: none !important;
}

/* ---------- scroll reveals (site.js adds .is-in) ---------- */
.js [data-reveal]:not(.is-in) {
	opacity: 0;
	transform: translateY(18px);
}

.js [data-reveal] {
	transition: opacity 0.7s var(--ease), transform 0.7s var(--ease);
}

@media (max-width: 760px) {
	.nav-links {
		gap: 0.9rem;
		font-size: 0.875rem;
	}

	.nav-links .nav-hide-s {
		display: none;
	}
}

@media (prefers-reduced-motion: reduce) {
	[data-header],
	.to-top,
	.to-top-tip,
	.js [data-reveal] {
		transition: none;
	}

	.js [data-reveal]:not(.is-in) {
		opacity: 1;
		transform: none;
	}
}