/* tabtango landing: the midnight ballroom. Ink navy and black, hairline borders, a faint floor
   grid, large crisp type, muted silver and dusty teal, two slow spotlights crossing. */

:root {
  --seed: #5f8f8b;
  --font: 'Inter Tight', ui-sans-serif, system-ui, -apple-system, 'Segoe UI', sans-serif;
  --serif: 'Instrument Serif', ui-serif, Georgia, serif;
  --ease: cubic-bezier(.2, .8, .2, 1);
  --wrap: 1180px;
}
html[data-theme='dark'] {
  --background: #05070b;
  --foreground: #e6ebf1;
  --surface: #0a0d14;
  --surface-2: #0e131c;
  --muted-foreground: #8d97a5;
  --border: rgba(200, 214, 230, 0.1);
  --line: rgba(200, 214, 230, 0.16);
  --silver: #c4cbd4;
  --teal: #86b5b0;
  --teal-soft: rgba(134, 181, 176, 0.12);
  --grid: rgba(200, 214, 230, 0.035);
  --glass: rgba(5, 7, 11, 0.72);
  --spot-core: rgba(190, 212, 226, 0.17);
  --spot-mid: rgba(134, 181, 176, 0.05);
}
html[data-theme='light'] {
  --background: #f3f4f6;
  --foreground: #10151d;
  --surface: #ffffff;
  --surface-2: #f7f8fa;
  --muted-foreground: #586270;
  --border: rgba(16, 24, 36, 0.1);
  --line: rgba(16, 24, 36, 0.16);
  --silver: #3c4552;
  --teal: #3f6d69;
  --teal-soft: rgba(63, 109, 105, 0.09);
  --grid: rgba(16, 24, 36, 0.045);
  --glass: rgba(243, 244, 246, 0.8);
  --spot-core: rgba(255, 255, 255, 0.95);
  --spot-mid: rgba(134, 181, 176, 0.12);
}

* { box-sizing: border-box; }
html { background: var(--background); scroll-behavior: smooth; scroll-padding-top: 76px; }
body.site {
  margin: 0;
  font-family: var(--font);
  color: var(--foreground);
  background:
    linear-gradient(var(--grid) 1px, transparent 1px) 0 0 / 64px 64px,
    linear-gradient(90deg, var(--grid) 1px, transparent 1px) 0 0 / 64px 64px,
    var(--background);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
.sprite { position: absolute; }
.ic { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; flex: none; }
.ic .ac { stroke: var(--teal); }
.btn .ic .ac { stroke: currentColor; }
.muted { color: var(--muted-foreground); }
.small { font-size: 13.5px; }
a { color: var(--teal); text-underline-offset: 3px; }
:focus-visible { outline: 2px solid var(--teal); outline-offset: 3px; }
.skip-link { position: absolute; left: 12px; top: -60px; z-index: 50; padding: 8px 12px; background: var(--surface); border: 1px solid var(--border); border-radius: 8px; color: var(--foreground); }
.skip-link:focus { top: 10px; }


/* ---------- nav ---------- */
.nav { position: sticky; top: 0; z-index: 30; display: flex; align-items: center; gap: 14px; height: 64px; padding: 0 max(16px, calc((100vw - var(--wrap)) / 2)); background: var(--glass); backdrop-filter: blur(14px) saturate(1.2); border-bottom: 1px solid var(--border); }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--foreground); text-decoration: none; font-weight: 650; font-size: 18px; letter-spacing: -0.015em; }
.nav-links { display: flex; gap: 22px; margin-left: 18px; }
.nav-links a { color: var(--muted-foreground); text-decoration: none; font-size: 14.5px; }
.nav-links a:hover { color: var(--foreground); }
.nav-gap { flex: 1; }
.theme-btn .ic-sun { display: none; }
html[data-theme='light'] .theme-btn .ic-sun { display: block; }
html[data-theme='light'] .theme-btn .ic-moon { display: none; }
.menu-btn { display: none; }

main, .foot { position: relative; z-index: 1; }

/* ---------- hero: the ballroom floor seen from above ---------- */
.kicker { margin: 0 0 14px; font-size: 13px; font-weight: 600; letter-spacing: 0.14em; text-transform: uppercase; color: var(--teal); }
.floor { position: relative; min-height: min(100svh, 980px); padding: clamp(72px, 12vh, 140px) 16px clamp(96px, 14vh, 160px); display: grid; place-items: center; overflow: hidden; isolation: isolate; border-bottom: 1px solid var(--border); }
.floor-tiles { position: absolute; inset: -20%; z-index: -3; background:
    repeating-linear-gradient(45deg, var(--grid) 0 1px, transparent 1px 56px),
    repeating-linear-gradient(-45deg, var(--grid) 0 1px, transparent 1px 56px);
  mask-image: radial-gradient(ellipse at 50% 45%, #000 20%, transparent 72%); }
.floor-spot { position: absolute; left: 50%; top: 46%; width: min(1100px, 130vw); aspect-ratio: 1; translate: -50% -50%; z-index: -2; border-radius: 50%; background: radial-gradient(circle, var(--spot-core) 0%, var(--spot-mid) 34%, transparent 66%); animation: sweep 26s ease-in-out infinite, breathe 9s ease-in-out infinite alternate; }
@keyframes breathe { to { scale: 1.06; opacity: 0.85; } }
/* The spotlight follows the dancers around the floor: a slow loop, never far from the title. */
@keyframes sweep {
  0%, 100% { translate: -50% -50%; }
  20% { translate: -64% -44%; }
  45% { translate: -56% -58%; }
  70% { translate: -38% -46%; }
  85% { translate: -44% -56%; }
}
.floor .trails { position: absolute; inset: 0; width: 100%; height: 100%; z-index: -1; }
.floor .hero-cursors { position: absolute; inset: 0; pointer-events: none; z-index: 2; }
.floor-copy { position: relative; z-index: 1; width: min(1280px, 100%); text-align: center; display: grid; justify-items: center; }
.split-title { margin: 0 0 26px; width: 100%; font-size: clamp(54px, 11.5vw, 188px); line-height: 0.9; letter-spacing: -0.055em; font-weight: 650; display: grid; gap: 0.04em; }
.split-title .line { display: block; white-space: nowrap; }
.split-title .line-a { justify-self: start; translate: 0 0; animation: slide-a 1.2s var(--ease) both; }
.split-title .line-b { justify-self: end; animation: slide-b 1.2s 0.12s var(--ease) both; }
.split-title em { font-family: var(--serif); font-style: italic; font-weight: 400; letter-spacing: -0.03em; color: var(--silver); }
@keyframes slide-a { from { opacity: 0; translate: -6vw 0; } }
@keyframes slide-b { from { opacity: 0; translate: 6vw 0; } }
.floor .hero-lead { margin: 0 auto 28px; max-width: 40em; font-size: clamp(17px, 1.5vw, 20px); line-height: 1.55; color: var(--muted-foreground); }
.floor .hero-cta { justify-content: center; }
.floor .hero-note { margin: 16px 0 0; font-size: 14px; color: var(--muted-foreground); }
.motion-ctl { position: absolute; right: clamp(12px, 3vw, 32px); top: clamp(12px, 2.5vh, 24px); z-index: 3; }
.motion-btn { gap: 8px; color: var(--muted-foreground); border: 1px solid var(--border); background: color-mix(in srgb, var(--background) 70%, transparent); backdrop-filter: blur(6px); border-radius: 999px; padding-inline: 12px; }
.motion-ic { width: 10px; height: 10px; display: inline-block; border-left: 3px solid currentColor; border-right: 3px solid currentColor; box-sizing: border-box; }
.motion-ic[data-paused='true'] { border: 0; border-left: 9px solid currentColor; border-top: 5px solid transparent; border-bottom: 5px solid transparent; }
.hc[hidden] { display: none; }
.crossing { position: absolute; left: 0; top: 0; width: clamp(200px, 26vw, 400px); z-index: 0; pointer-events: none; animation: cross 34s -13s linear infinite; offset-path: path('M -420 820 C 200 640, 500 520, 900 380 S 1500 120, 2000 -180'); offset-rotate: 0deg; }
.crossing .dancers { width: 100%; height: auto; filter: drop-shadow(0 26px 30px rgba(0, 0, 0, 0.45)); opacity: 0.92; }
@keyframes cross { from { offset-distance: 0%; } to { offset-distance: 100%; } }
.hc { position: absolute; left: 0; top: 0; will-change: transform; color: var(--c); }
.hc svg { width: 22px; height: 22px; filter: drop-shadow(0 1px 2px rgba(0, 0, 0, 0.5)); }
.hc svg path { fill: var(--c); stroke: #05070b; stroke-width: 1.4; stroke-linejoin: round; }
.hc span { position: absolute; left: 16px; top: 16px; padding: 4px 9px; border-radius: 999px; background: var(--c); color: #05070b; font: 600 12px/1 var(--font); white-space: nowrap; }
.hc-ripple { position: absolute; width: 40px; height: 40px; margin: -20px 0 0 -20px; border-radius: 50%; border: 2px solid var(--c); animation: ripple 0.8s var(--ease) forwards; }
@keyframes ripple { from { scale: 0.2; opacity: 1; } to { scale: 1.8; opacity: 0; } }
.dancers-light { display: none; }
html[data-theme='light'] .dancers-light { display: block; }
html[data-theme='light'] .dancers-dark { display: none; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ---------- steps on a diagonal, with footprints ---------- */
.block-head { text-align: center; display: grid; justify-items: center; }
.block-head .block-title { max-width: 20ch; }
.diagonal { position: relative; margin-top: 40px; }
.diag-line { position: absolute; inset: 0; width: 100%; height: 100%; pointer-events: none; }
.diag-line path { fill: none; stroke: var(--line); stroke-width: 1.5; stroke-dasharray: 2 9; vector-effect: non-scaling-stroke; }
.dance { list-style: none; margin: 0; padding: 0; display: grid; gap: clamp(28px, 5vw, 64px); }
.dance-step { position: relative; width: min(720px, 100%); margin-left: calc((100% - min(720px, 100%)) * var(--i) / 2); }
.step-card { position: relative; border: 1px solid var(--border); border-radius: 20px; background: linear-gradient(180deg, var(--surface-2), var(--surface)); overflow: hidden; box-shadow: 0 30px 70px -40px rgba(0, 0, 0, 0.7); }
.step-card .step-art { margin: 0; border-bottom: 1px solid var(--border); }
.step-card h3 { margin: 18px 22px 8px; font-size: 22px; letter-spacing: -0.02em; }
.step-card p { margin: 0 22px 24px; color: var(--muted-foreground); line-height: 1.6; }
.step-card .step-n { position: absolute; top: 14px; left: 14px; z-index: 1; display: grid; place-items: center; width: 34px; height: 34px; border-radius: 50%; background: var(--background); border: 1px solid var(--line); color: var(--teal); font-weight: 700; }
.prints { position: absolute; top: -46px; left: 10px; display: flex; gap: 10px; }
.prints span { display: block; opacity: 0; translate: 0 6px; transition: opacity 0.5s var(--ease), translate 0.5s var(--ease); transition-delay: calc(var(--k) * 0.22s); }
.prints span:nth-child(even) { translate: 0 14px; }
.dance-step.is-in .prints span { opacity: 1; translate: 0 0; }
.dance-step.is-in .prints span:nth-child(even) { translate: 0 8px; }
.print { width: 30px; height: 30px; fill: none; stroke: var(--teal); stroke-width: 2.2; stroke-linecap: round; }
.prints span:nth-child(2) .print { rotate: 28deg; }
.prints span:nth-child(3) .print { rotate: -12deg; }

/* ---------- blocks ---------- */
.tt-block { max-width: var(--wrap); margin: 0 auto; padding: clamp(56px, 8vw, 112px) 16px 0; }
.block-title { margin: 0 0 16px; font-size: clamp(30px, 4vw, 52px); line-height: 1.05; letter-spacing: -0.035em; font-weight: 640; max-width: 22ch; text-wrap: balance; }
.block-lead { margin: 0 0 32px; font-size: 18px; line-height: 1.6; color: var(--muted-foreground); max-width: 46em; }
.step-art { margin: 0; border-bottom: 1px solid var(--border); }
.ill { display: block; width: 100%; height: auto; }
.ill-light { display: none; }
html[data-theme='light'] .ill-light { display: block; }
html[data-theme='light'] .ill-dark { display: none; }
.step-n { display: inline-grid; place-items: center; width: 28px; height: 28px; border-radius: 50%; border: 1px solid var(--line); color: var(--teal); font-weight: 650; font-size: 13px; margin-bottom: 12px; }
.tt-compare { display: grid; grid-template-columns: 1fr; gap: 0; border: 1px solid var(--border); border-radius: 18px; overflow: hidden; background: var(--surface); }
.tt-compare .col { padding: 24px 26px; }
.tt-compare .col-ext { border-top: 1px solid var(--border); background: linear-gradient(180deg, var(--teal-soft), transparent); }
.tt-compare h3 { display: flex; gap: 10px; align-items: center; margin: 0 0 12px; font-size: 18px; }
.tt-compare ul { margin: 0; padding: 0; list-style: none; display: grid; gap: 10px; }
.tt-compare li { padding-left: 22px; position: relative; color: var(--silver); line-height: 1.5; }
.tt-compare li::before { content: ''; position: absolute; left: 2px; top: 0.55em; width: 9px; height: 5px; border-left: 1.5px solid var(--teal); border-bottom: 1.5px solid var(--teal); rotate: -45deg; }
.ext-grid { margin-top: 18px; display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1fr); gap: 18px; align-items: start; }
.ext-art { margin: 0; border-radius: 18px; overflow: hidden; }
.install { border: 1px solid var(--border); border-radius: 18px; background: var(--surface); padding: 24px; display: grid; gap: 14px; justify-items: start; }
.install h3 { margin: 0; font-size: 20px; }
.install-steps { margin: 0; padding: 0; list-style: none; counter-reset: s; display: grid; gap: 12px; }
.install-steps li { counter-increment: s; display: grid; grid-template-columns: 30px 1fr; column-gap: 10px; }
.install-steps li::before { content: counter(s); grid-row: span 2; width: 26px; height: 26px; border-radius: 50%; display: grid; place-items: center; border: 1px solid var(--line); color: var(--teal); font-size: 12.5px; font-weight: 650; }
.install-steps span { color: var(--muted-foreground); font-size: 15px; line-height: 1.5; }
.install .btn { gap: 8px; }
.install p { margin: 0; }
.perms { margin-top: 18px; border: 1px solid var(--border); border-radius: 18px; background: var(--surface); padding: 24px 26px; }
.perms h3 { margin: 0 0 14px; font-size: 20px; }
.perms dl { margin: 0; display: grid; gap: 0; }
.perms dl > div { display: grid; grid-template-columns: 1fr; gap: 6px; padding: 12px 0; border-top: 1px solid var(--border); }
.perms dt code { font-size: 13.5px; color: var(--teal); background: var(--teal-soft); padding: 3px 8px; border-radius: 6px; }
.perms dd { margin: 0; color: var(--muted-foreground); line-height: 1.55; }
.no-control { margin-top: 18px; display: flex; gap: 16px; align-items: flex-start; padding: 22px 26px; border-radius: 18px; border: 1px solid var(--line); background: var(--surface-2); }
.no-control .ic { width: 28px; height: 28px; margin-top: 2px; }
.no-control h3 { margin: 0 0 6px; font-size: 19px; }
.no-control p { margin: 0; color: var(--muted-foreground); line-height: 1.6; }
.follow figure { margin: 0 auto; max-width: 760px; }
.ext-art { margin: 18px auto 0; max-width: 820px; }

/* ---------- download ---------- */
.dl { display: grid; grid-template-columns: 1fr; text-align: center; border: 1px solid var(--line); border-radius: 22px; overflow: hidden; background: radial-gradient(ellipse at 20% 0%, var(--teal-soft), transparent 60%), var(--surface); box-shadow: 0 40px 90px -50px rgba(0, 0, 0, 0.8); }
.dl-main { padding: clamp(28px, 5vw, 56px); display: grid; justify-items: center; }
.dl-main .block-title { max-width: none; }
.dl-main .block-lead { max-width: 40em; }
.dl-side { justify-items: start; }
.dl-side > p { grid-column: 1 / -1; }
.dl-main .block-title { margin-bottom: 12px; }
.dl-main .block-lead { margin-bottom: 24px; font-size: 17px; }
.dl-btn { gap: 10px; font-size: 17px; padding-inline: 26px; height: 54px; }
.dl-btn .ic { width: 22px; height: 22px; }
.dl-facts { display: flex; flex-wrap: wrap; justify-content: center; gap: 10px 28px; margin: 22px 0 14px; }
.dl-facts dt { font-size: 12px; letter-spacing: 0.12em; text-transform: uppercase; color: var(--muted-foreground); }
.dl-facts dd { margin: 2px 0 0; font-weight: 600; font-variant-numeric: tabular-nums; }
.dl-facts code, .dl-sum code { font-family: ui-monospace, Menlo, Consolas, monospace; font-size: 13px; }
.dl-sum { display: flex; flex-wrap: wrap; justify-content: center; gap: 6px 10px; align-items: baseline; margin: 0 0 6px; padding: 12px 14px; border-radius: 12px; border: 1px solid var(--border); background: var(--surface-2); }
.dl-sum span { font-size: 12px; font-weight: 650; letter-spacing: 0.1em; color: var(--teal); }
.dl-sum code { overflow-wrap: anywhere; color: var(--silver); }
.dl-side { padding: clamp(24px, 4vw, 44px); border-top: 1px solid var(--border); text-align: left; background: var(--surface-2); display: grid; align-content: start; gap: 10px; }
.dl-side h3 { display: flex; gap: 10px; align-items: center; margin: 6px 0 0; font-size: 17px; }
.dl-side ul { margin: 0 0 8px; padding: 0; list-style: none; display: grid; gap: 8px; }
.dl-side li { position: relative; padding-left: 22px; color: var(--silver); line-height: 1.5; }
.can li::before { content: ''; position: absolute; left: 2px; top: 0.55em; width: 9px; height: 5px; border-left: 1.5px solid var(--teal); border-bottom: 1.5px solid var(--teal); rotate: -45deg; }
.cannot li::before { content: ''; position: absolute; left: 3px; top: 0.75em; width: 10px; height: 1.5px; background: var(--muted-foreground); }
.dl-side p { margin: 4px 0 0; }
.guide-title { margin: 40px 0 16px; font-size: 22px; letter-spacing: -0.02em; }
.guide { list-style: none; margin: 0 0 12px; padding: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.guide li { border: 1px solid var(--border); border-radius: 18px; overflow: hidden; background: var(--surface); }
.guide figure { margin: 0; border-bottom: 1px solid var(--border); }
.guide-copy { padding: 18px 20px 22px; }
.guide-n { display: inline-flex; align-items: center; gap: 8px; padding: 4px 10px 4px 8px; border-radius: 999px; border: 1px solid var(--line); color: var(--teal); font-size: 13px; margin-bottom: 10px; }
.guide-n .ic { width: 18px; height: 18px; }
.guide h4 { margin: 0 0 6px; font-size: 18px; letter-spacing: -0.015em; }
.guide p { margin: 0; color: var(--muted-foreground); line-height: 1.6; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr)); gap: 14px; margin-top: 28px; }
.mini { border: 1px solid var(--border); border-radius: 16px; background: var(--surface); padding: 22px; }
.mini .ic { width: 26px; height: 26px; margin-bottom: 10px; }
.mini h3 { margin: 0 0 8px; font-size: 18px; letter-spacing: -0.015em; }
.mini p { margin: 0; color: var(--muted-foreground); line-height: 1.6; }
.faq { display: grid; gap: 10px; max-width: 860px; margin-top: 20px; }
.faq details { border: 1px solid var(--border); border-radius: 14px; background: var(--surface); padding: 0 20px; }
.faq summary { cursor: pointer; padding: 18px 0; font-weight: 600; font-size: 17px; list-style: none; display: flex; justify-content: space-between; gap: 12px; }
.faq summary::after { content: '+'; color: var(--teal); font-weight: 400; font-size: 22px; line-height: 1; }
.faq details[open] summary::after { content: '\2212'; }
.faq p { margin: 0 0 18px; color: var(--muted-foreground); line-height: 1.6; }
.cta { max-width: var(--wrap); margin: clamp(64px, 9vw, 120px) auto 0; padding: 48px 16px; text-align: center; display: grid; justify-items: center; gap: 18px; border-top: 1px solid var(--border); }
.cta img { width: 200px; height: auto; }
.cta h2 { margin: 0; font-size: clamp(30px, 4vw, 48px); letter-spacing: -0.035em; }

/* ---------- footer ---------- */
.foot { margin-top: 48px; border-top: 1px solid var(--border); background: var(--surface); }
.foot-grid { max-width: var(--wrap); margin: 0 auto; padding: 40px 16px 56px; display: grid; grid-template-columns: 1fr; gap: 32px; }
.foot p { color: var(--muted-foreground); line-height: 1.6; margin: 12px 0 0; }
.foot-title { margin: 0 0 12px; font-size: 13px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted-foreground); font-weight: 600; }
.more { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: 10px 18px; }
.more a { font-weight: 600; text-decoration: none; }
.more small { display: block; color: var(--muted-foreground); font-size: 13px; }

/* ---------- reveal on scroll ---------- */
.js .reveal { opacity: 0; translate: 0 18px; transition: opacity 0.8s var(--ease), translate 0.8s var(--ease); }
.js .reveal.is-in { opacity: 1; translate: 0 0; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .reveal { opacity: 1; translate: 0 0; transition: none; }
  .floor-spot, .split-title .line, .crossing { animation: none; }
  .crossing { offset-distance: 42%; }
  .prints span { opacity: 1; transition: none; }
  .hc-ripple { animation: none; opacity: 0; }
}

/* ---------- responsive, 320 to 2560 ---------- */
@media (min-width: 1800px) {
  :root { --wrap: 1480px; }
  body.site { font-size: 18px; }
}
@media (max-width: 1080px) {
  .dance-step { margin-left: calc((100% - min(560px, 100%)) * var(--i) / 2); }
  .ext-grid { grid-template-columns: 1fr; }
  .guide { grid-template-columns: 1fr; max-width: 560px; }
  .dl { grid-template-columns: 1fr; }
  .dl-side { border-left: 0; border-top: 1px solid var(--border); }
}
@media (max-width: 860px) {
  .nav-links { display: none; position: absolute; top: 64px; left: 0; right: 0; flex-direction: column; gap: 0; margin: 0; padding: 8px 16px 16px; background: var(--background); border-bottom: 1px solid var(--border); }
  .nav-links.is-open { display: flex; }
  .nav-links a { padding: 12px 0; border-bottom: 1px solid var(--border); font-size: 16px; }
  .menu-btn { display: inline-flex; }
  .tt-compare { grid-template-columns: 1fr; }
  .tt-compare .col-ext { border-left: 0; border-top: 1px solid var(--border); }
  .perms dl > div { grid-template-columns: 1fr; gap: 6px; }
  .foot-grid { grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
  .nav { gap: 6px; }
  .nav-cta { display: none; }
  .hero-cta .btn, .dl-btn { width: 100%; }
  .split-title .line-a, .split-title .line-b { justify-self: center; white-space: normal; }
  .prints { left: 8px; }
  .hc span { font-size: 10px; padding: 3px 7px; }
}