/* ==========================================================================
   Obstoon — Layout: shell, containers, header, mobile nav, footer, rhythm
   ========================================================================== */

.shell {
  display: flex;
  flex-direction: column;
  min-height: 100svh;
  isolation: isolate;
}

.container {
  width: 100%;
  max-width: var(--width-content);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.container--narrow {
  max-width: 880px;
}

/* Wide compositions: two-column rows, staggered panels, layer stacks. */
.container--composition {
  max-width: var(--width-composition);
}

/* ---- Section rhythm ---- */
.section {
  position: relative;
  padding-block: var(--space-3xl);
}

.section--tight {
  padding-block: var(--space-2xl);
}

.section--loose {
  padding-block: var(--space-4xl);
}

/* Hairline between stacked sections */
.section + .section::before {
  content: "";
  position: absolute;
  inset-inline: var(--gutter);
  top: 0;
  height: 1px;
  background: linear-gradient(
    90deg,
    transparent,
    var(--border) 18%,
    var(--border) 82%,
    transparent
  );
}

.section-head {
  display: grid;
  gap: var(--space-sm);
  max-width: 74ch;
  margin-bottom: var(--space-2xl);
}

.section-head__title {
  font-size: var(--text-3xl);
}

.section-head--split {
  max-width: none;
  grid-template-columns: minmax(0, 1fr);
  align-items: end;
}

@media (min-width: 62rem) {
  .section-head--split {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    gap: var(--space-xl) var(--space-2xl);
  }

  .section-head--split .section-head__aside {
    padding-bottom: 0.35em;
  }
}

.section-head__aside {
  color: var(--text-soft);
  font-size: var(--text-md);
  line-height: var(--leading-relaxed);
  max-width: 48ch;
}

/* ==========================================================================
   Header
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  isolation: isolate;
}

.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: color-mix(in srgb, var(--bg) 76%, transparent);
  border-bottom: 1px solid transparent;
  backdrop-filter: blur(16px) saturate(150%);
  -webkit-backdrop-filter: blur(16px) saturate(150%);
  transition: border-color var(--dur-3) var(--ease-out),
    background-color var(--dur-3) var(--ease-out);
}

.site-header[data-stuck="true"]::before {
  border-bottom-color: var(--border);
  background: color-mix(in srgb, var(--bg) 90%, transparent);
}

.site-header__inner {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  min-height: var(--header-height);
}

/* ---- Brand: typographic wordmark (no invented parent logo) ---- */
.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 0.5rem;
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 660;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
  margin-right: auto;
}

.brand:hover {
  color: var(--text);
}

.brand__dot {
  width: 7px;
  height: 7px;
  border-radius: 2px;
  background: linear-gradient(140deg, var(--accent), var(--accent-2));
  transform: translateY(-1px) rotate(45deg);
  flex: none;
}

.brand__sub {
  font-family: var(--font-mono);
  font-size: var(--text-3xs);
  font-weight: 500;
  letter-spacing: var(--tracking-widest);
  color: var(--text-faint);
  text-transform: uppercase;
}

/* ---- Desktop navigation ---- */
.site-nav {
  display: none;
}

@media (min-width: 64rem) {
  .site-nav {
    display: block;
  }
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-3xs);
}

.site-nav__link {
  position: relative;
  display: block;
  padding: 0.5rem 0.8rem;
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: -0.005em;
  color: var(--text-muted);
  text-decoration: none;
  border-radius: var(--radius-2xs);
  transition: color var(--dur-2) var(--ease-out),
    background-color var(--dur-2) var(--ease-out);
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0.8rem;
  right: 0.8rem;
  bottom: 0.15rem;
  height: 1.5px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transform: scaleX(0);
  transform-origin: left center;
  opacity: 0;
  transition: transform var(--dur-3) var(--ease-out),
    opacity var(--dur-3) var(--ease-out);
}

.site-nav__link:hover {
  color: var(--text);
  background: var(--surface-inset);
}

.site-nav__link[aria-current="page"] {
  color: var(--text);
}

.site-nav__link[aria-current="page"]::after {
  transform: scaleX(1);
  opacity: 1;
}

/* ---- Header actions ---- */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3xs);
}

.icon-btn {
  position: relative;
  display: inline-grid;
  place-items: center;
  width: 40px;
  height: 40px;
  color: var(--text-muted);
  background: var(--surface-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius-2xs);
  transition: color var(--dur-2) var(--ease-out),
    border-color var(--dur-2) var(--ease-out),
    background-color var(--dur-2) var(--ease-out),
    transform var(--dur-2) var(--ease-out);
}

.icon-btn:hover {
  color: var(--text);
  border-color: var(--border-strong);
  background: var(--surface-3);
}

.icon-btn:active {
  transform: translateY(1px);
}

.icon-btn svg {
  width: 18px;
  height: 18px;
}

@media (hover: hover) {
  .icon-btn:hover {
    box-shadow: var(--shadow-sm);
  }
}

/* ==========================================================================
   Theme control — segmented Sun / Moon
   The audit found a single generic moon icon, which communicated no current
   state and hid the fact that both options exist. This is a segmented switch:
   both states are visible at once, a thumb marks the active one, and the
   button carries an accessible label that names the action.
   ========================================================================== */
.theme-switch {
  --switch-w: 62px;
  position: relative;
  display: inline-grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  width: var(--switch-w);
  height: 34px;
  padding: 3px;
  color: var(--text-muted);
  background: var(--surface-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  cursor: pointer;
  isolation: isolate;
  transition: color var(--dur-2) var(--ease-out),
    border-color var(--dur-2) var(--ease-out),
    background-color var(--dur-2) var(--ease-out),
    box-shadow var(--dur-2) var(--ease-out);
}

/* Visible focus ring — the switch is keyboard reachable and must show it */
.theme-switch:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (hover: hover) {
  .theme-switch:hover {
    color: var(--text);
    border-color: var(--border-strong);
    background: var(--surface-2);
  }
}

.theme-switch__thumb {
  position: absolute;
  top: 3px;
  bottom: 3px;
  left: 3px;
  width: calc(50% - 3px);
  border-radius: var(--radius-pill);
  background: linear-gradient(
    150deg,
    var(--accent) 0%,
    color-mix(in srgb, var(--accent) 58%, var(--accent-2)) 100%
  );
  box-shadow: var(--glow-accent);
  transition: transform var(--dur-4) var(--ease-spring);
}

/* The thumb rests under the icon that is live: in Dark it sits on the moon,
   in Light on the sun. (These were inverted, so in both themes the pill
   sat under the muted icon while the opposite side glowed.) */
[data-theme="dark"] .theme-switch__thumb {
  transform: translateX(100%);
}

[data-theme="light"] .theme-switch__thumb {
  transform: none;
}

.theme-switch__opt {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  height: 100%;
  color: inherit;
  transition: color var(--dur-3) var(--ease-out);
}

.theme-switch__opt svg {
  width: 16px;
  height: 16px;
}

/* The active segment reads as ink on the thumb; the inactive stays muted */
.theme-switch__opt--sun {
  color: var(--text-faint);
}

.theme-switch__opt--moon {
  color: var(--text-faint);
}

[data-theme="dark"] .theme-switch__opt--moon,
[data-theme="light"] .theme-switch__opt--sun {
  color: var(--on-accent);
}

@media (hover: hover) {
  .theme-switch:hover .theme-switch__opt--sun,
  .theme-switch:hover .theme-switch__opt--moon {
    color: var(--text-muted);
  }

  [data-theme="dark"] .theme-switch:hover .theme-switch__opt--moon,
  [data-theme="light"] .theme-switch:hover .theme-switch__opt--sun {
    color: var(--on-accent);
  }
}

/* Narrow viewports: the control must not crowd the brand */
@media (max-width: 26rem) {
  .theme-switch {
    --switch-w: 54px;
    height: 32px;
  }

  .theme-switch__opt svg {
    width: 15px;
    height: 15px;
  }
}

/* ---- Reduced motion: no thumb slide ---- */
@media (prefers-reduced-motion: reduce) {
  .theme-switch__thumb {
    transition: none;
  }
}

/* ---- Mobile toggle ---- */
.nav-toggle {
  display: inline-grid;
}

@media (min-width: 64rem) {
  .nav-toggle {
    display: none;
  }
}

.nav-toggle__bars {
  position: relative;
  width: 16px;
  height: 11px;
}

.nav-toggle__bars span {
  position: absolute;
  left: 0;
  width: 100%;
  height: 1.6px;
  border-radius: 2px;
  background: currentColor;
  transition: transform var(--dur-3) var(--ease-out),
    opacity var(--dur-2) var(--ease-out);
}

.nav-toggle__bars span:nth-child(1) {
  top: 0;
}
.nav-toggle__bars span:nth-child(2) {
  top: 50%;
  transform: translateY(-50%);
}
.nav-toggle__bars span:nth-child(3) {
  bottom: 0;
}

[aria-expanded="true"] .nav-toggle__bars span:nth-child(1) {
  transform: translateY(4.7px) rotate(45deg);
}
[aria-expanded="true"] .nav-toggle__bars span:nth-child(2) {
  opacity: 0;
  transform: scaleX(0.2);
}
[aria-expanded="true"] .nav-toggle__bars span:nth-child(3) {
  transform: translateY(-4.7px) rotate(-45deg);
}

/* ---- Mobile navigation panel ---- */
.mobile-nav {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 80;
  display: grid;
  grid-template-rows: 1fr auto;
  padding: var(--space-lg) var(--gutter) var(--space-lg);
  background: color-mix(in srgb, var(--bg) 94%, transparent);
  backdrop-filter: blur(22px) saturate(140%);
  -webkit-backdrop-filter: blur(22px) saturate(140%);
  border-top: 1px solid var(--border);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-1.5rem);
  transition: opacity var(--dur-3) var(--ease-out),
    transform var(--dur-4) var(--ease-out),
    visibility 0s linear var(--dur-4);
  overflow-y: auto;
  overscroll-behavior: contain;
}

.mobile-nav[data-open="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  transition-delay: 0s;
}

@media (min-width: 64rem) {
  .mobile-nav {
    display: none;
  }
}

.mobile-nav__list {
  display: grid;
  align-content: start;
  gap: var(--space-3xs);
}

.mobile-nav__item {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity var(--dur-4) var(--ease-out),
    transform var(--dur-4) var(--ease-out);
}

.mobile-nav[data-open="true"] .mobile-nav__item {
  opacity: 1;
  transform: translateY(0);
}

.mobile-nav[data-open="true"] .mobile-nav__item:nth-child(1) { transition-delay: 60ms; }
.mobile-nav[data-open="true"] .mobile-nav__item:nth-child(2) { transition-delay: 110ms; }
.mobile-nav[data-open="true"] .mobile-nav__item:nth-child(3) { transition-delay: 160ms; }
.mobile-nav[data-open="true"] .mobile-nav__item:nth-child(4) { transition-delay: 210ms; }
.mobile-nav[data-open="true"] .mobile-nav__item:nth-child(5) { transition-delay: 260ms; }

.mobile-nav__link {
  display: flex;
  align-items: baseline;
  gap: var(--space-sm);
  padding: var(--space-sm) 0;
  font-size: var(--text-xl);
  font-weight: 620;
  letter-spacing: var(--tracking-snug);
  color: var(--text);
  text-decoration: none;
  border-bottom: 1px solid var(--border);
  transition: color var(--dur-2) var(--ease-out),
    padding-left var(--dur-3) var(--ease-out);
}

.mobile-nav__link:hover,
.mobile-nav__link[aria-current="page"] {
  color: var(--accent);
  padding-left: var(--space-2xs);
}

.mobile-nav__index {
  font-family: var(--font-mono);
  font-size: var(--text-3xs);
  letter-spacing: var(--tracking-wide);
  color: var(--text-faint);
}

.mobile-nav__foot {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  padding-top: var(--space-lg);
  font-size: var(--text-2xs);
  color: var(--text-faint);
}

.mobile-nav__legal {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2xs) var(--space-sm);
}

.mobile-nav__legal a {
  color: var(--text-muted);
  text-decoration: none;
}

.mobile-nav__legal a:hover {
  color: var(--accent);
}

/* Lock scroll while the panel is open */
body[data-nav-open="true"] {
  overflow: hidden;
}

/* ==========================================================================
   Page shell
   ========================================================================== */
.page-main {
  flex: 1 0 auto;
}

.skip-offset {
  scroll-margin-top: calc(var(--header-height) + var(--space-xl));
}

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
  position: relative;
  margin-top: var(--space-3xl);
  padding-block: var(--space-2xl) var(--space-lg);
  border-top: 1px solid var(--border);
  background: linear-gradient(
    180deg,
    transparent,
    color-mix(in srgb, var(--accent) 4%, transparent)
  );
}

.site-footer::before {
  content: "";
  position: absolute;
  inset-inline: 0;
  top: -1px;
  height: 1px;
  background: linear-gradient(
    90deg,
    transparent,
    var(--accent-line) 30%,
    color-mix(in srgb, var(--accent-2) 40%, transparent) 70%,
    transparent
  );
}

.footer-grid {
  display: grid;
  gap: var(--space-xl);
  grid-template-columns: minmax(0, 1fr);
}

@media (min-width: 48rem) {
  .footer-grid {
    grid-template-columns: minmax(0, 1.4fr) repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 64rem) {
  .footer-grid {
    grid-template-columns: minmax(0, 1.7fr) repeat(3, minmax(0, 1fr));
    gap: var(--space-2xl);
  }
}

.footer-brand,
.footer-col {
  min-width: 0;
}

.footer-brand__statement {
  margin-top: var(--space-md);
  max-width: 34ch;
  font-size: var(--text-sm);
  line-height: var(--leading-relaxed);
  color: var(--text-muted);
}

.footer-col__title {
  font-family: var(--font-mono);
  font-size: var(--text-3xs);
  font-weight: 500;
  letter-spacing: var(--tracking-widest);
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: var(--space-sm);
}

.footer-col__list {
  display: grid;
  gap: 0.55rem;
}

.footer-col__list a {
  display: inline-block;
  font-size: var(--text-sm);
  color: var(--text-soft);
  text-decoration: none;
  transition: color var(--dur-2) var(--ease-out),
    transform var(--dur-2) var(--ease-out);
}

.footer-col__list a:hover {
  color: var(--accent);
  transform: translateX(3px);
}

.footer-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  margin-top: var(--space-2xl);
  padding-top: var(--space-md);
  border-top: 1px solid var(--border);
  font-size: var(--text-2xs);
  color: var(--text-faint);
}

.footer-bar__legal {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2xs) var(--space-md);
}

.footer-bar a {
  color: var(--text-muted);
  text-decoration: none;
}

.footer-bar a:hover {
  color: var(--accent);
}

/* Oversized wordmark closing the page */
.footer-mark {
  display: block;
  margin-top: var(--space-xl);
  font-family: var(--font-display);
  font-size: clamp(3.5rem, 15vw, 13rem);
  font-weight: 700;
  line-height: 0.82;
  letter-spacing: -0.04em;
  text-align: center;
  color: transparent;
  background: linear-gradient(
    180deg,
    color-mix(in srgb, var(--text) 15%, transparent) 0%,
    color-mix(in srgb, var(--text) 2%, transparent) 78%
  );
  -webkit-background-clip: text;
  background-clip: text;
  user-select: none;
  pointer-events: none;
}