/* ============================================================
   Sei Website — design system
   Adopted from the Claude Design mockup (claude-design/project/).
   Single font: Chakra Petch (Bender stand-in).
   Single accent: light blue (--accent).
============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Chakra+Petch:wght@300;400;500;600;700&display=swap');

:root {
  --ink-0: #ffffff;
  --ink-1: #c8cee0;
  --ink-2: #7b819a;
  --bg-0:  #050813;
  --bg-1:  #0a0f24;
  --bg-2:  #121833;
  --accent:      #8ec5ff;
  --accent-soft: rgba(142, 197, 255, 0.18);
  --accent-line: rgba(142, 197, 255, 0.45);
  --border:      rgba(255, 255, 255, 0.08);

  --f: 'Chakra Petch', 'Bender', system-ui, sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--f);
  background: var(--bg-0);
  color: var(--ink-0);
  font-size: 18px;
  line-height: 1.6;
  font-weight: 400;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  background-image:
    radial-gradient(ellipse 1000px 700px at 80% -10%, rgba(60, 80, 150, 0.18), transparent 60%),
    radial-gradient(ellipse 900px 600px at 10% 110%, rgba(60, 80, 150, 0.18), transparent 60%),
    linear-gradient(180deg, #050813 0%, #060a1a 50%, #04060f 100%);
}

/* ====================== WHITE FADE-IN ====================== */
.curtain {
  position: fixed;
  inset: 0;
  background: #ffffff;
  z-index: 9999;
  pointer-events: none;
  opacity: 1;
  transition: opacity 0.8s ease-out;
}
.curtain.is-hidden { opacity: 0; }

/* ====================== HERO BG VIDEO ====================== */
.bg-video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 0;
  pointer-events: none;
  user-select: none;
}
.bg-overlay {
  position: absolute;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  background: rgba(5, 8, 19, 0.45);
}

/* ============================== NAV ============================== */
.nav {
  position: fixed; top: 0; left: 0; right: 0;
  z-index: 100;
  display: flex; align-items: center; justify-content: space-between;
  padding: 22px 40px;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition: background 0.4s ease, border-color 0.4s ease, backdrop-filter 0.4s ease;
}
.nav.is-scrolled,
.nav.is-static {
  background: rgba(5, 8, 19, 0.7);
  backdrop-filter: blur(14px) saturate(120%);
  -webkit-backdrop-filter: blur(14px) saturate(120%);
  border-bottom-color: var(--border);
}
.nav__brand {
  display: inline-flex; align-items: center; gap: 12px;
  color: var(--ink-0);
  text-decoration: none;
  font-weight: 700;
  letter-spacing: 0.28em;
  font-size: 15px;
}
.nav__links {
  display: inline-flex; align-items: center; gap: 32px;
}
.nav__link {
  color: var(--ink-0);
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.22em;
  font-size: 13px;
  opacity: 0.85;
  transition: opacity 0.2s;
}
.nav__link:hover,
.nav__link.is-active { opacity: 1; }
.nav__brand-mark {
  display: inline-flex; align-items: center;
  color: var(--ink-0);
  text-decoration: none;
}

/* comet logo (CSS) — placeholder, swap in real mark whenever */
.comet { position: relative; width: 24px; height: 24px; display: inline-block; }
.comet__head {
  position: absolute; right: 2px; top: 50%; transform: translateY(-50%);
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--ink-0);
  box-shadow: 0 0 10px var(--ink-0);
}
.comet__tail {
  position: absolute; right: 8px; top: 50%;
  width: 20px; height: 1.5px; transform: translateY(-50%) rotate(-14deg);
  transform-origin: right center;
  background: linear-gradient(to left, rgba(255, 255, 255, 0.95), transparent);
}

/* ============================== HERO ============================== */
.hero {
  position: relative;
  height: 100vh;
  min-height: 640px;
  display: flex; flex-direction: column;
  justify-content: flex-end;
  align-items: center;
  padding: 0 40px 80px;
  overflow: hidden;
}
.hero__overlay {
  position: absolute; inset: 0; z-index: 2;
  pointer-events: none;
  background: linear-gradient(180deg, rgba(5, 8, 19, 0.35) 0%, rgba(5, 8, 19, 0.0) 30%, rgba(5, 8, 19, 0.75) 100%);
}
.hero__content {
  position: relative; z-index: 3;
  text-align: center;
  max-width: 880px;
  width: 100%;
}
.hero__wordmark {
  display: block;
  width: clamp(180px, 30vw, 380px);
  height: auto;
  margin: 0 auto 28px;
  filter: invert(1);
}
.hero__tagline {
  font-size: clamp(19px, 1.8vw, 23px);
  font-weight: 400;
  letter-spacing: 0.05em;
  margin: 0 auto 36px;
  max-width: 640px;
  color: var(--ink-1);
  text-wrap: balance;
  line-height: 1.5;
}

/* ========================= INSTALL BUTTONS ========================= */
.cta-row {
  display: flex; gap: 14px; justify-content: center; flex-wrap: wrap;
}
.install {
  appearance: none; border: 0; cursor: pointer;
  display: inline-flex; align-items: center; gap: 12px;
  padding: 13px 24px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.14);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  color: var(--ink-0);
  text-decoration: none;
  font-family: var(--f);
  font-weight: 600;
  font-size: 14px;
  letter-spacing: 0.1em;
  transition: background 0.2s, border-color 0.2s, transform 0.18s;
}
.install:hover {
  background: rgba(142, 197, 255, 0.12);
  border-color: var(--accent-line);
  transform: translateY(-1px);
}
.install__icon { width: 16px; height: 16px; flex-shrink: 0; }
.cta-version {
  margin: 14px 0 0;
  text-align: center;
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--ink-2);
  text-transform: lowercase;
}

/* ============================ SECTIONS ============================ */
section { position: relative; z-index: 1; }

.section-title {
  font-weight: 600;
  font-size: clamp(34px, 4vw, 56px);
  letter-spacing: 0.01em;
  line-height: 1.05;
  margin: 0;
  text-wrap: balance;
}

/* compat strip */
.strip {
  padding: 100px 40px 100px;
  text-align: center;
  max-width: 1100px;
  margin: 0 auto;
}
.strip__label {
  font-size: 16px;
  letter-spacing: 0.08em;
  color: var(--ink-2);
  margin: 0 0 28px;
  font-weight: 400;
}
.strip__label--mid { margin-top: 36px; }
.strip__row {
  display: flex; flex-wrap: wrap; justify-content: center; align-items: center;
  gap: 14px 24px;
}
.game-logo {
  display: block;
  width: auto;
  object-fit: contain;
  user-select: none;
  -webkit-user-drag: none;
}
.game-logo--mc { height: 64px; }
.game-logo--skyrim { height: 64px; filter: brightness(1.05); }
.strip__joiner {
  font-size: 16px;
  color: var(--ink-2);
  letter-spacing: 0.12em;
}

/* feature blocks */
.feature {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 64px;
  align-items: center;
  padding: 100px 80px;
  max-width: 1300px;
  margin: 0 auto;
}
.feature--right .feature__media { order: 2; }
.feature--right .feature__body  { order: 1; }
.feature__title {
  font-weight: 600;
  font-size: clamp(30px, 3.4vw, 46px);
  line-height: 1.1;
  letter-spacing: 0.005em;
  margin: 0 0 20px;
  text-wrap: balance;
}
.feature__copy {
  font-size: 19px;
  font-weight: 400;
  color: var(--ink-1);
  max-width: 50ch;
  margin: 0;
  line-height: 1.6;
}

/* media placeholders */
.media {
  /* FEATURE ART — drop a still image, GIF, or short video into .feature__media
     (replace this .media element). Dashed border + label disappear once swapped. */
  position: relative;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.025);
  border: 1px dashed rgba(255, 255, 255, 0.14);
  aspect-ratio: 16 / 10;
  display: flex; align-items: center; justify-content: center;
  overflow: hidden;
}
.media__label {
  font-size: 12px;
  letter-spacing: 0.22em;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.55);
  text-transform: uppercase;
  padding: 6px 14px;
  background: rgba(0, 0, 0, 0.4);
  border: 1px solid var(--border);
  display: inline-flex; align-items: center; gap: 10px;
  text-align: center;
  max-width: 75%;
}
.media__label::before {
  content: ""; width: 5px; height: 5px; border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 6px var(--accent);
  flex-shrink: 0;
}
.media--tall { aspect-ratio: 4 / 5; }

/* app screenshot — bare, no window chrome */
.app-shot {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 14px;
  border: 1px solid var(--border);
}

/* ============================ PRICING ============================ */
.pricing { padding: 100px 40px 80px; }
.pricing__head {
  text-align: center;
  margin: 0 auto 56px;
  max-width: 700px;
}
.tiers {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  max-width: 1100px;
  margin: 0 auto;
}
.tier {
  position: relative;
  padding: 36px 28px;
  background: rgba(255, 255, 255, 0.03);
  border-radius: 18px;
  border: 1px solid var(--border);
  display: flex; flex-direction: column;
  transition: border-color 0.2s, transform 0.2s;
}
.tier:hover { border-color: var(--accent-line); transform: translateY(-2px); }
.tier--accent {
  border-color: var(--accent-line);
  background: rgba(142, 197, 255, 0.05);
}
.tier--soon {
  background: rgba(255, 255, 255, 0.015);
  border-color: var(--border);
  filter: grayscale(0.85);
  opacity: 0.55;
}
.tier--soon:hover {
  border-color: var(--border);
  transform: none;
}
.tier--soon .tier__amount { color: var(--ink-1); }
.tier__soon {
  display: inline-block;
  align-self: flex-start;
  margin: 0 0 14px;
  padding: 4px 10px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.22em;
  color: var(--ink-1);
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--border);
  border-radius: 999px;
  text-transform: uppercase;
}
.tier__name {
  font-weight: 700;
  font-size: 18px;
  letter-spacing: 0.2em;
  margin: 0 0 18px;
  color: var(--ink-0);
}
.tier__price {
  display: flex; align-items: baseline; gap: 8px;
  margin-bottom: 18px;
}
.tier__amount {
  font-weight: 600;
  font-size: 48px;
  line-height: 1;
  letter-spacing: 0.01em;
}
.tier--accent .tier__amount { color: var(--accent); }
.tier__period {
  color: var(--ink-2);
  font-size: 15px;
  letter-spacing: 0.04em;
}
.tier__desc {
  color: var(--ink-1);
  font-size: 17px;
  font-weight: 400;
  margin: 0;
  flex: 1;
  line-height: 1.55;
}

/* ============================ FINAL CTA =========================== */
.final {
  padding: 100px 40px 100px;
  text-align: center;
}
.final__inner {
  max-width: 760px;
  margin: 0 auto;
}
.final__title {
  font-weight: 600;
  font-size: clamp(32px, 3.8vw, 50px);
  margin: 0 0 32px;
  line-height: 1.05;
  letter-spacing: 0.005em;
}

/* =============================== FAQ ============================== */
.faq {
  padding: 40px 40px 120px;
  max-width: 820px;
  margin: 0 auto;
}
.faq__head { text-align: center; margin-bottom: 40px; }
.faq__list { display: flex; flex-direction: column; gap: 10px; }
.faq__item {
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}
.faq__item summary {
  cursor: pointer;
  list-style: none;
  display: flex; align-items: center; justify-content: space-between;
  padding: 22px 26px;
  font-weight: 500;
  font-size: 19px;
  letter-spacing: 0.005em;
}
.faq__item summary::-webkit-details-marker { display: none; }
.faq__plus {
  width: 16px; height: 16px;
  position: relative; flex-shrink: 0;
  margin-left: 16px;
}
.faq__plus::before,
.faq__plus::after {
  content: ""; position: absolute;
  background: var(--accent);
  transition: transform 0.25s;
}
.faq__plus::before { top: 50%; left: 0; right: 0; height: 1.5px; transform: translateY(-50%); }
.faq__plus::after  { left: 50%; top: 0; bottom: 0; width: 1.5px; transform: translateX(-50%); }
.faq__item[open] .faq__plus::after { transform: translateX(-50%) scaleY(0); }
.faq__a {
  padding: 0 24px 22px;
  color: var(--ink-1);
  font-size: 17px;
  font-weight: 400;
  line-height: 1.6;
}

/* ========================== BUILD PAGE ============================ */
.b-hero {
  position: relative;
  padding: 200px 40px 80px;
  text-align: center;
  max-width: 880px;
  margin: 0 auto;
}
.b-hero__title {
  font-weight: 600;
  font-size: clamp(38px, 4.8vw, 64px);
  line-height: 1.05;
  letter-spacing: 0.005em;
  margin: 0 0 24px;
  text-wrap: balance;
}
.b-hero__sub {
  font-size: 20px;
  color: var(--ink-1);
  margin: 0 auto;
  max-width: 56ch;
  text-wrap: balance;
  line-height: 1.55;
}

.dev-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  max-width: 980px;
  margin: 0 auto;
  padding: 0 40px 100px;
}
.dev-card {
  display: grid;
  grid-template-columns: 80px 1fr auto;
  align-items: center;
  gap: 32px;
  padding: 36px;
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid var(--border);
  border-radius: 18px;
  transition: border-color 0.2s, background 0.2s;
}
.dev-card:hover {
  border-color: var(--accent-line);
  background: rgba(142, 197, 255, 0.04);
}
.dev-card__num {
  font-weight: 700;
  font-size: 38px;
  letter-spacing: 0.04em;
  color: var(--accent);
  line-height: 1;
}
.dev-card__title {
  font-weight: 600;
  font-size: 22px;
  margin: 0 0 8px;
  letter-spacing: 0.005em;
}
.dev-card__copy {
  color: var(--ink-1);
  font-size: 17px;
  margin: 0;
  max-width: 60ch;
  line-height: 1.6;
}
.dev-card__cta {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 12px 20px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.14);
  color: var(--ink-0);
  text-decoration: none;
  font-family: var(--f);
  font-weight: 600;
  letter-spacing: 0.14em;
  font-size: 12px;
  white-space: nowrap;
  transition: background 0.2s, border-color 0.2s, transform 0.2s;
}
.dev-card__cta:hover {
  background: rgba(142, 197, 255, 0.12);
  border-color: var(--accent-line);
  transform: translateY(-1px);
}
.dev-card__cta svg { width: 14px; height: 14px; }

/* ============================= FOOTER ============================= */
.foot {
  padding: 60px 40px 32px;
  border-top: 1px solid var(--border);
}
.foot__inner {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 40px;
  max-width: 1200px;
  margin: 0 auto;
}
.foot__brand-row { display: flex; align-items: center; gap: 12px; }
.foot__logo { height: 32px; width: auto; filter: invert(1); opacity: 0.95; }
.foot__tag { margin: 18px 0 0; color: var(--ink-2); font-size: 14px; max-width: 28ch; }
.foot__col { display: flex; flex-direction: column; gap: 10px; }
.foot__heading {
  font-size: 12px;
  letter-spacing: 0.22em;
  color: var(--ink-2);
  margin: 0 0 8px;
  text-transform: uppercase;
  font-weight: 600;
}
.foot__col a {
  color: var(--ink-1); text-decoration: none; font-size: 14px;
  transition: color 0.2s;
}
.foot__col a:hover { color: var(--ink-0); }
.socials { display: flex; gap: 10px; margin-top: 4px; }
.social {
  width: 36px; height: 36px;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border);
  color: var(--ink-0);
  text-decoration: none;
  transition: background 0.2s, border-color 0.2s;
}
.social:hover { background: rgba(142, 197, 255, 0.1); border-color: var(--accent-line); }
.social svg { width: 15px; height: 15px; }
.foot__base {
  max-width: 1200px; margin: 50px auto 0;
  padding-top: 22px;
  border-top: 1px solid var(--border);
  display: flex; justify-content: space-between; align-items: center;
  font-size: 13px;
  color: var(--ink-2);
  letter-spacing: 0.04em;
}

/* ============================= REVEAL ============================= */
[data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
[data-reveal].is-in { opacity: 1; transform: translateY(0); }

/* ============================ RESPONSIVE ========================== */
@media (max-width: 960px) {
  .nav { padding: 16px 20px; }
  .nav__links { gap: 22px; }
  .hero { padding: 0 20px 60px; }
  .feature {
    grid-template-columns: 1fr;
    gap: 32px;
    padding: 70px 24px;
  }
  .feature--right .feature__media { order: 0; }
  .feature--right .feature__body  { order: 0; }
  .tiers { grid-template-columns: 1fr; }
  .foot__inner { grid-template-columns: 1fr 1fr; }
  .foot__base { flex-direction: column; gap: 8px; }
}

@media (max-width: 760px) {
  .b-hero { padding: 140px 24px 60px; }
  .dev-card {
    grid-template-columns: auto 1fr;
    grid-template-rows: auto auto;
    gap: 20px;
    padding: 28px;
  }
  .dev-card__cta { grid-column: 1 / -1; justify-self: start; }
}