/* Components — header, nav, theme toggle, mobile overlay */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  border-bottom: 1px solid transparent;
  background: color-mix(in srgb, var(--bg) 72%, transparent);
  transition:
    border-color 220ms var(--ease-out),
    background-color 220ms var(--ease-out),
    backdrop-filter 220ms var(--ease-out),
    -webkit-backdrop-filter 220ms var(--ease-out);
}

.site-header.is-scrolled {
  border-bottom-color: var(--line);
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  backdrop-filter: blur(12px) saturate(1.2);
  -webkit-backdrop-filter: blur(12px) saturate(1.2);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  height: var(--header-h);
}

.site-logo {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--ink);
  white-space: nowrap;
}

.site-logo:hover {
  color: var(--accent);
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

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

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

.site-nav__link {
  display: inline-flex;
  align-items: center;
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--step--1);
  font-weight: 400;
  letter-spacing: 0.04em;
  text-decoration: none;
  color: var(--ink-muted);
  border-radius: var(--radius-md);
  transition: color 180ms var(--ease-out), background-color 180ms var(--ease-out);
}

.site-nav__link:hover {
  color: var(--ink);
  background: color-mix(in srgb, var(--surface-2) 80%, transparent);
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  background: var(--surface);
  color: var(--ink);
  transition:
    color 180ms var(--ease-out),
    border-color 180ms var(--ease-out),
    background-color 180ms var(--ease-out),
    transform 220ms var(--ease-spring);
}

.icon-btn:hover {
  color: var(--accent);
  border-color: var(--accent-dim);
}

.icon-btn:active {
  transform: scale(0.94);
}

.icon-btn svg {
  width: 1.05rem;
  height: 1.05rem;
}

.theme-toggle .icon-sun {
  display: none;
}

[data-theme="light"] .theme-toggle .icon-moon {
  display: none;
}

[data-theme="light"] .theme-toggle .icon-sun {
  display: block;
}

.nav-toggle {
  display: none;
}

.nav-toggle__bar {
  display: block;
  width: 1rem;
  height: 1.5px;
  background: currentColor;
  border-radius: 1px;
  transition:
    transform 220ms var(--ease-out),
    opacity 180ms var(--ease-out);
}

.nav-toggle__bar + .nav-toggle__bar {
  margin-top: 4px;
}

body.nav-open {
  overflow: hidden;
}

body.nav-open .nav-toggle__bar:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}

body.nav-open .nav-toggle__bar:nth-child(2) {
  opacity: 0;
}

body.nav-open .nav-toggle__bar:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

@media (max-width: 768px) {
  .nav-toggle {
    display: inline-flex;
    flex-direction: column;
  }

  .site-nav {
    position: fixed;
    inset: 0;
    z-index: 90;
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: calc(var(--header-h) + var(--space-8)) var(--gutter) var(--space-8);
    background: color-mix(in srgb, var(--bg) 96%, transparent);
    backdrop-filter: blur(16px) saturate(1.15);
    -webkit-backdrop-filter: blur(16px) saturate(1.15);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    overflow-y: auto;
    transition:
      opacity 220ms var(--ease-out),
      visibility 220ms var(--ease-out);
  }

  body.nav-open .site-nav {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    gap: var(--space-3);
    width: 100%;
    margin-block: auto;
  }

  .site-nav__link {
    font-size: var(--step-2);
    font-family: var(--font-display);
    font-weight: 500;
    letter-spacing: -0.01em;
    padding: var(--space-3) var(--space-2);
    color: var(--ink);
  }
}