/* ===== Design Tokens ===== */
:root {
  --color-bg-primary: #0D0D0D;
  --color-bg-secondary: #181818;
  --color-bg-tertiary: #262626;
  --color-text-primary: #FFFFFF;
  --color-text-secondary: #E6E6E6;
  --color-accent: #60DC71;
  --color-accent-hover: #4FC760;
  --font-family: 'Satoshi', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --container-max: 1120px;
  --container-padding: 1.5rem;
  --header-height: 72px;
}

/* ===== Reset ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
}

body {
  font-family: var(--font-family);
  font-weight: 400;
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
  background: var(--color-bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

/* ===== Utilities ===== */
.container {
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-padding);
}

.text-accent {
  color: var(--color-accent);
}

.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;
}

/* ===== Button ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--font-family);
  font-weight: 500;
  font-size: 0.9375rem;
  padding: 0.875rem 2rem;
  border-radius: 6px;
  border: none;
  cursor: pointer;
  transition: transform 0.15s ease, background-color 0.15s ease;
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, #60DC71 0%, #4AC85E 50%, #3BB84D 100%);
  color: #FFFFFF;
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2), inset 0 1px 0 rgba(255, 255, 255, 0.15);
}

.btn-primary:hover {
  background: linear-gradient(135deg, #6FE57F 0%, #55D068 50%, #45C356 100%);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(96, 220, 113, 0.25), inset 0 1px 0 rgba(255, 255, 255, 0.15);
}

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

/* ===== Header ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-height);
  display: flex;
  align-items: center;
  background: rgba(13, 13, 13, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease;
}

.header.scrolled {
  border-bottom-color: rgba(255, 255, 255, 0.06);
}

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

.header-logo img {
  height: 32px;
  width: auto;
}

.header-cta {
  font-size: 0.875rem;
  padding: 0.625rem 1.5rem;
}

/* Mobile nav - hidden on desktop */
.mobile-nav {
  display: none;
}

/* Mobile menu button */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--color-text-primary);
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: currentColor;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.menu-toggle span + span {
  margin-top: 6px;
}

/* ===== Section Base ===== */
section {
  padding-block: 6rem;
}

.section-alt {
  background: var(--color-bg-secondary);
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}

/* ===== Hero ===== */
.hero {
  padding-top: calc(var(--header-height) + 4rem);
  padding-bottom: 0;
  background: linear-gradient(180deg, #262626 0%, #0D0D0D 100%);
  overflow: visible;
}

.hero .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: end;
  gap: 3rem;
}

.hero-content {
  max-width: 540px;
  padding-bottom: 4rem;
}

.hero h1 {
  font-size: clamp(2.25rem, 4vw + 0.5rem, 3.5rem);
  font-weight: 700;
  line-height: 1.15;
  color: var(--color-text-primary);
  margin-bottom: 1.25rem;
}

.hero-sub {
  font-size: clamp(1.0625rem, 1.2vw + 0.5rem, 1.25rem);
  font-weight: 400;
  line-height: 1.6;
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
}

.hero .btn {
  margin-top: 0.5rem;
}

.hero-image {
  display: flex;
  justify-content: center;
  align-items: flex-end;
}

.hero-image img {
  max-height: 560px;
  width: auto;
  object-fit: contain;
  filter: drop-shadow(0 8px 32px rgba(0, 0, 0, 0.4));
  position: relative;
}

/* ===== Problem + Solution ===== */
.problem-solution .container {
  max-width: 760px;
}

.problem-solution h2 {
  font-size: clamp(1.75rem, 3vw + 0.25rem, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text-primary);
  margin-bottom: 2rem;
}

.problem-solution p {
  margin-bottom: 1.5rem;
  font-size: 1.0625rem;
}

.problem-solution p:last-child {
  margin-bottom: 0;
}

/* ===== Mechanism ===== */
.mechanism h2 {
  font-size: clamp(1.75rem, 3vw + 0.25rem, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text-primary);
  margin-bottom: 3rem;
  text-align: center;
}

.mechanism-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.mechanism-card {
  background: var(--color-bg-tertiary);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 12px;
  padding: 2rem;
}

.mechanism-card .material-symbols-outlined {
  font-size: 36px;
  color: var(--color-accent);
  margin-bottom: 1rem;
  display: block;
}

.mechanism-card h3 {
  font-size: 1.1875rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: 0.75rem;
  line-height: 1.3;
}

.mechanism-card p {
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--color-text-secondary);
}

/* ===== Authority ===== */
.authority .container {
  max-width: 760px;
}

.authority h2 {
  font-size: clamp(1.75rem, 3vw + 0.25rem, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text-primary);
  margin-bottom: 2rem;
}

.authority p {
  font-size: 1.0625rem;
  margin-bottom: 1.5rem;
}

.authority p:last-child {
  margin-bottom: 0;
}

/* ===== Bottom CTA ===== */
.bottom-cta {
  text-align: center;
  background: linear-gradient(180deg, var(--color-bg-primary) 0%, #262626 100%);
}

.bottom-cta h2 {
  font-size: clamp(1.75rem, 3vw + 0.25rem, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text-primary);
  margin-bottom: 1rem;
}

.bottom-cta p {
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
  font-size: 1.0625rem;
}

/* ===== Footer ===== */
.footer {
  padding-block: 3rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-logo img {
  height: 24px;
  width: auto;
  opacity: 0.5;
}

.footer-copy {
  font-size: 0.8125rem;
  color: rgba(255, 255, 255, 0.35);
}

/* ===== Focus ===== */
:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  :root {
    --header-height: 64px;
  }

  section {
    padding-block: 4rem;
  }

  .menu-toggle {
    display: flex;
    flex-direction: column;
    gap: 0;
  }

  .header-cta {
    display: none;
  }

  .header-cta.mobile-cta {
    display: inline-flex;
    width: 100%;
    justify-content: center;
    margin-top: 1rem;
  }

  .mobile-nav {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: rgba(13, 13, 13, 0.97);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    padding: 1.5rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  }

  .mobile-nav.is-open {
    display: block;
  }

  .mobile-nav-link {
    display: block;
    padding: 0.75rem 0;
    font-size: 1rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  }

  .mobile-nav-link:last-of-type {
    border-bottom: none;
  }

  .hero {
    padding-top: calc(var(--header-height) + 2.5rem);
    padding-bottom: 0;
  }

  .hero .container {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .hero-content {
    max-width: 100%;
    padding-bottom: 0;
  }

  .hero .btn {
    margin-inline: auto;
  }

  .hero-image img {
    max-height: 380px;
    margin-inline: auto;
  }

  .mechanism-grid {
    grid-template-columns: 1fr;
  }

  .footer .container {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *, *::before, *::after {
    transition: none !important;
  }
}