body {
  font-family: var(--font-sans);
  background:
    radial-gradient(ellipse 80% 50% at 20% 0%, var(--lc-mesh-1), transparent 50%),
    radial-gradient(ellipse 60% 40% at 80% 30%, var(--lc-mesh-2), transparent 50%),
    radial-gradient(ellipse 70% 50% at 50% 100%, var(--lc-mesh-3), transparent 50%),
    linear-gradient(180deg, var(--lc-bg-deep), var(--bg-primary));
  background-attachment: fixed;
  color: var(--text-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::selection {
  background: var(--accent-primary);
  color: var(--text-inverse);
}

::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--gray-200);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--gray-300);
}

.container {
  position: relative;
  z-index: var(--z-base);
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-8);
}

.container--narrow {
  max-width: var(--max-width-narrow);
}

.container--wide {
  max-width: var(--max-width-wide);
}

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-sticky);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--space-8);
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  transition: transform var(--duration-base) var(--ease-out),
              background var(--duration-base) var(--ease-out);
}

.nav--scrolled {
  background: var(--glass-bg-hover);
  border-bottom-color: var(--border-color);
}

.nav--hidden {
  transform: translateY(-100%);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  text-decoration: none;
  color: var(--text-primary);
  user-select: none;
}

.nav-logo-text {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--weight-bold);
  letter-spacing: -0.02em;
}

.nav-back {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-3);
  margin-left: var(--space-2);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  color: var(--text-tertiary);
  font-size: var(--text-xs);
  font-weight: var(--weight-medium);
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--duration-fast) var(--ease-out),
              border-color var(--duration-fast) var(--ease-out),
              background var(--duration-fast) var(--ease-out);
}

.nav-back:hover {
  color: var(--text-primary);
  border-color: var(--border-color-hover);
  background: var(--surface-hover);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out),
              background var(--duration-fast) var(--ease-out);
}

.nav-links a:hover {
  color: var(--text-primary);
  background: var(--surface-hover);
}

.nav-links a.active {
  color: var(--accent-primary);
  background: rgba(var(--accent-primary-rgb), 0.06);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-2);
  cursor: pointer;
  z-index: calc(var(--z-sticky) + 1);
  background: none;
  border: none;
}

.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--text-primary);
  border-radius: var(--radius-full);
  transition: all var(--duration-base) var(--ease-out);
}

.nav-toggle.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

.footer {
  position: relative;
  z-index: var(--z-base);
  border-top: 1px solid var(--border-color);
  padding: var(--space-16) var(--space-8) var(--space-8);
  background: var(--bg-secondary);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-8);
  max-width: var(--max-width);
  margin: 0 auto;
  padding-bottom: var(--space-8);
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.footer-logo {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--weight-bold);
  color: var(--text-primary);
}

.footer-brand p {
  color: var(--text-secondary);
  font-size: var(--text-sm);
  line-height: var(--leading-relaxed);
  max-width: 280px;
}

.footer-col h4 {
  font-size: var(--text-2xs);
  font-weight: var(--weight-semibold);
  text-transform: uppercase;
  letter-spacing: var(--tracking-wider);
  color: var(--text-tertiary);
  margin-bottom: var(--space-4);
}

.footer-col a {
  display: block;
  color: var(--text-secondary);
  font-size: var(--text-sm);
  padding: var(--space-1) 0;
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

.footer-col a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  padding-top: var(--space-6);
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-4);
}

.footer-bottom p {
  color: var(--text-tertiary);
  font-size: var(--text-xs);
}

.footer-social {
  display: flex;
  gap: var(--space-4);
}

.footer-social a {
  color: var(--text-tertiary);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

.footer-social a:hover {
  color: var(--text-primary);
}

.section {
  padding: var(--space-24) 0;
  position: relative;
}

.section--sm { padding: var(--space-12) 0; }
.section--lg { padding: var(--space-32) 0; }

.section-header {
  text-align: center;
  margin-bottom: var(--space-16);
}

.section-label {
  display: inline-block;
  font-size: var(--text-2xs);
  font-weight: var(--weight-semibold);
  text-transform: uppercase;
  letter-spacing: var(--tracking-widest);
  color: var(--text-tertiary);
  margin-bottom: var(--space-3);
}

.section-title {
  font-size: clamp(1.8rem, 3.5vw, var(--text-3xl));
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  line-height: var(--leading-tight);
  margin-bottom: var(--space-4);
  color: var(--text-primary);
}

.section-desc {
  color: var(--text-secondary);
  max-width: 540px;
  margin: 0 auto;
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
}

.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: var(--space-6); }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-6); }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: var(--space-6); }
.grid-auto { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--space-6); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-center { align-items: center; justify-content: center; }
.flex-between { justify-content: space-between; }
.flex-wrap { flex-wrap: wrap; }
.gap-2 { gap: var(--space-2); }
.gap-4 { gap: var(--space-4); }
.gap-6 { gap: var(--space-6); }
.gap-8 { gap: var(--space-8); }

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-muted { color: var(--text-tertiary); }
.text-secondary { color: var(--text-secondary); }

.mt-4 { margin-top: var(--space-4); }
.mt-8 { margin-top: var(--space-8); }
.mt-16 { margin-top: var(--space-16); }
.mb-4 { margin-bottom: var(--space-4); }
.mb-8 { margin-bottom: var(--space-8); }
.mb-16 { margin-bottom: var(--space-16); }

.section-divider {
  width: 100%;
  height: 1px;
  background: var(--border-color);
  border: none;
}

.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: var(--z-dropdown);
  width: 40px;
  height: 40px;
  padding: 0;
  border: 1px solid var(--glass-border);
  border-radius: 999px;
  display: grid;
  place-items: center;
  color: var(--text-primary);
  background: var(--glass-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  cursor: pointer;
  overflow: hidden;
  isolation: isolate;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translate3d(0, 10px, 0) scale(0.96);
  transition: opacity 220ms ease, visibility 220ms ease, transform 220ms ease, border-color 220ms ease, background-color 220ms ease;
}

.back-to-top.is-visible,
.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: translate3d(0, 0, 0) scale(1);
}

.back-to-top:hover {
  border-color: var(--accent-primary);
  transform: translate3d(0, -2px, 0) scale(1.03);
}

.back-to-top__progress {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  transform: rotate(-90deg);
  transform-origin: 50% 50%;
}

.back-to-top__track,
.back-to-top__bar {
  fill: none;
  cx: 20;
  cy: 20;
  r: 17;
  stroke-width: 2px;
}

.back-to-top__track {
  stroke: var(--border-color);
}

.back-to-top__bar {
  stroke: var(--accent-primary);
  stroke-linecap: round;
  stroke-dasharray: 100;
  stroke-dashoffset: 100;
  transition: stroke 220ms ease;
  will-change: stroke-dashoffset;
}

.back-to-top__icon {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 100%;
  height: 100%;
  font-size: 18px;
  font-weight: 700;
  line-height: 1;
  transform: translateY(-1px);
  user-select: none;
  pointer-events: none;
}

.page-header {
  text-align: center;
  padding: calc(var(--nav-height) + var(--space-20)) var(--space-6) var(--space-16);
  position: relative;
}

.page-header__label {
  font-size: var(--text-2xs);
  font-weight: var(--weight-semibold);
  text-transform: uppercase;
  letter-spacing: var(--tracking-widest);
  color: var(--text-tertiary);
  margin-bottom: var(--space-4);
}

.page-header__title {
  font-size: clamp(2.2rem, 4vw, var(--text-4xl));
  font-weight: var(--weight-bold);
  letter-spacing: var(--tracking-tight);
  margin-bottom: var(--space-4);
  color: var(--text-primary);
}

.page-header__desc {
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto;
  font-size: var(--text-base);
  line-height: var(--leading-relaxed);
}

.toast-container {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.toast {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-5);
  background: var(--bg-elevated);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  animation: slideInRight var(--duration-base) var(--ease-out);
  max-width: 360px;
}

.toast__icon { flex-shrink: 0; font-size: var(--text-sm); }
.toast__message { font-size: var(--text-sm); color: var(--text-primary); }
.toast__close { color: var(--text-tertiary); cursor: pointer; margin-left: var(--space-2); font-size: var(--text-xs); }

@media (max-width: 1024px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
  }

  .container {
    padding: 0 var(--space-4);
  }

  .nav {
    padding: 0 var(--space-4);
  }

  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    flex-direction: column;
    padding: calc(var(--nav-height) + var(--space-6)) var(--space-6);
    background: var(--bg-elevated);
    border-left: 1px solid var(--border-color);
    transition: right var(--duration-slow) var(--ease-out);
    z-index: var(--z-sticky);
    gap: var(--space-1);
  }

  .nav-links.open {
    right: 0;
  }

  .nav-links a {
    width: 100%;
    font-size: var(--text-base);
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius-md);
  }

  .nav-toggle {
    display: flex;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: var(--space-6);
  }

  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }

  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }

  .section {
    padding: var(--space-16) 0;
  }

  .section--lg {
    padding: var(--space-20) 0;
  }
}

@media (max-width: 480px) {
  .grid-auto {
    grid-template-columns: 1fr;
  }
}

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