:root {
  --b612-yellow: #F5C518;
  --b612-black: #111111;
  --b612-pink: #E6197A;
  --text: #1a1a1a;
  --bg: #ffffff;
  --bg-alt: #f7f7f7;
  --header-h: 64px;

  /* Spring-like easing (Apple "Designing Fluid Interfaces"): critically damped settle vs. instant tap response */
  --ease-settle: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-press: cubic-bezier(0.4, 0, 0.2, 1);
}

* { box-sizing: border-box; }

html {
  scroll-padding-top: var(--header-h);
}

body {
  margin: 0;
  font: 100%/1.6 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  font-optical-sizing: auto;
  color: var(--text);
  background: var(--bg);
}

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

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- Header: translucent material, sticky ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--header-h);
  display: flex;
  align-items: center;
  background: rgba(17, 17, 17, 0.72);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  color: #fff;
  transition: background 200ms var(--ease-press), border-color 200ms var(--ease-press), box-shadow 200ms var(--ease-press);
}

.site-header.is-scrolled {
  background: rgba(17, 17, 17, 0.85);
  border-bottom-color: rgba(255, 255, 255, 0.14);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.08);
}

.header-inner {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  color: var(--b612-yellow);
  font-weight: 800;
  font-size: 1.3rem;
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-header nav {
  display: flex;
  align-items: center;
}

.site-header nav a {
  position: relative;
  color: #fff;
  text-decoration: none;
  margin-left: 28px;
  font-size: 0.95rem;
  padding: 4px 0;
  transition: color 120ms ease-out;
}

.site-header nav a::after {
  content: "";
  position: absolute;
  left: 0; bottom: -2px;
  width: 100%;
  height: 1px;
  background: var(--b612-yellow);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 200ms var(--ease-settle);
}

.site-header nav a:hover {
  color: var(--b612-yellow);
}

.site-header nav a:hover::after {
  transform: scaleX(1);
}

/* Hamburger — hidden on desktop */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 0;
  border: 0;
  background: transparent;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: #fff;
  transition: transform 200ms var(--ease-settle), opacity 150ms var(--ease-press);
}

.nav-toggle:active span {
  transition-duration: 80ms;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---------- Hero ---------- */

.hero {
  background: var(--b612-yellow);
  padding: 96px 0;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  line-height: 1.05;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
}

.hero p {
  font-size: 1.1rem;
  margin: 0 auto 32px;
  max-width: 46ch;
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-block;
  padding: 14px 28px;
  border-radius: 999px;
  background: var(--b612-black);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  letter-spacing: 0.01em;
  transform: translateZ(0) scale(1);
  transition: transform 150ms var(--ease-press), box-shadow 200ms var(--ease-settle), background 150ms var(--ease-press);
}

.btn:hover {
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.18);
  transform: translateY(-2px) scale(1);
}

.btn:active {
  transform: scale(0.96);
  transition-duration: 100ms;
}

.btn-outline {
  background: transparent;
  color: var(--b612-black);
  border: 1.5px solid var(--b612-black);
}

/* ---------- Sections ---------- */

.section {
  padding: 72px 0;
  scroll-margin-top: var(--header-h);
}

.section.alt {
  background: var(--bg-alt);
}

.section h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-bottom: 28px;
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
}

.card {
  border: 1px solid #e5e5e5;
  border-radius: 12px;
  padding: 22px;
  background: #fff;
  transition: transform 250ms var(--ease-settle), box-shadow 250ms var(--ease-settle);
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: 0 16px 32px rgba(0, 0, 0, 0.08);
}

.card:active {
  transform: translateY(-2px) scale(0.99);
  transition-duration: 100ms;
}

.card h3 {
  letter-spacing: -0.01em;
}

/* ---------- Scroll reveal ---------- */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 600ms var(--ease-settle), transform 600ms var(--ease-settle);
}

.reveal.is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- Footer ---------- */

.site-footer {
  background: var(--b612-black);
  color: #ccc;
  text-align: center;
  padding: 24px 0;
  font-size: 0.85rem;
  letter-spacing: 0.01em;
}

/* ---------- Responsive nav ---------- */

@media (max-width: 720px) {
  .nav-toggle {
    display: flex;
  }

  .site-header nav {
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    padding: 12px 20px 20px;
    background: rgba(17, 17, 17, 0.92);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    opacity: 0;
    transform: translateY(-8px);
    pointer-events: none;
    transition: opacity 200ms var(--ease-settle), transform 200ms var(--ease-settle);
  }

  .site-header nav.is-open {
    opacity: 1;
    transform: none;
    pointer-events: auto;
  }

  .site-header nav a {
    margin-left: 0;
    padding: 10px 0;
    width: 100%;
  }
}

/* ---------- Motion & transparency preferences ---------- */

@media (prefers-reduced-motion: no-preference) {
  html {
    scroll-behavior: smooth;
  }
}

@media (prefers-reduced-motion: reduce) {
  .reveal {
    transition: opacity 200ms ease;
    transform: none;
  }
  .card, .btn, .nav-toggle span, .site-header nav {
    transition-duration: 1ms;
  }
  .card:hover, .btn:hover {
    transform: none;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .site-header,
  .site-header nav {
    background: var(--b612-black);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}