/* ═══ HEADER & MOBILE MENU ═══ */
.site-header,
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 1.25rem var(--gutter);
  transition: background 0.4s, backdrop-filter 0.4s;
}

.site-header--scrolled,
.header--scrolled {
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.site-header__inner,
.header__inner {
  max-width: var(--max);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-header__logo,
.header__logo {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 600;
  letter-spacing: -0.04em;
  text-decoration: none;
  color: var(--fg);
}

.site-header__logo-mark,
.header__logo span {
  color: var(--signal);
}

.site-header__logo-text {
  margin-left: 0.5rem;
}

.site-header__nav,
.header__nav {
  display: flex;
  align-items: center;
  gap: 2.5rem;
}

.site-header__nav a,
.header__link {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  text-decoration: none;
  transition: color 0.3s;
  position: relative;
}

.site-header__nav a::after,
.header__link::after {
  content: "";
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1px;
  background: var(--signal);
  transition: width 0.4s var(--ease-signal);
}

.site-header__nav a:hover,
.site-header__cta:hover,
.header__link:hover,
.header__link--active {
  color: var(--fg);
}

.site-header__nav a:hover::after,
.header__link:hover::after {
  width: 100%;
}

.site-header__cta {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.65rem 1.25rem;
  border: 1px solid var(--line);
  border-radius: 100px;
  transition: border-color 0.3s, background 0.3s, color 0.3s;
}

.site-header__cta:hover {
  border-color: var(--signal);
  background: var(--signal);
  color: var(--signal-ink);
}

.site-header__cta::after {
  display: none;
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle--header {
  width: 2.25rem;
  height: 2.25rem;
}

.site-header__menu-btn,
.menu-btn {
  display: none;
  width: 2.5rem;
  height: 2.5rem;
  border: none;
  background: transparent;
  cursor: pointer;
  position: relative;
  z-index: 1002;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
}

.site-header__menu-btn span,
.menu-btn__bar {
  display: block;
  width: 1.5rem;
  height: 1px;
  background: var(--fg);
  transition: transform 0.4s var(--ease-signal), opacity 0.3s;
}

.site-header__menu-btn.menu-btn--open span:nth-child(1),
.menu-btn--open .menu-btn__bar:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.site-header__menu-btn.menu-btn--open span:nth-child(2),
.menu-btn--open .menu-btn__bar:nth-child(2) {
  opacity: 0;
}

.site-header__menu-btn.menu-btn--open span:nth-child(3),
.menu-btn--open .menu-btn__bar:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.header__actions {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle {
  width: 2.5rem;
  height: 2.5rem;
  border: 1px solid var(--line);
  border-radius: 50%;
  background: transparent;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--fg);
  transition: border-color 0.3s, color 0.3s;
}

.theme-toggle:hover {
  border-color: var(--signal);
  color: var(--signal);
}

.theme-toggle svg {
  width: 1rem;
  height: 1rem;
}

.theme-toggle__icon {
  font-size: 0.9rem;
  line-height: 1;
}

.theme-toggle__icon--moon {
  display: none;
}

[data-theme="light"] .theme-toggle__icon--sun {
  display: none;
}

[data-theme="light"] .theme-toggle__icon--moon {
  display: block;
}

.mobile-menu__footer {
  position: absolute;
  bottom: 2rem;
  left: 0;
  right: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
}

.mobile-menu__location {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.mobile-menu__link--cta {
  color: var(--signal);
}

/* Mobile overlay */
.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: 1001;
  background: var(--bg);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.mobile-menu--open {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

.mobile-menu__nav {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
}

.mobile-menu__link {
  font-family: var(--font-display);
  font-size: clamp(2rem, 8vw, 3.5rem);
  font-weight: 500;
  letter-spacing: -0.03em;
  color: var(--fg);
  text-decoration: none;
  opacity: 0;
  transform: translateY(2rem);
}

.mobile-menu__cta {
  margin-top: 2rem;
  opacity: 0;
  transform: translateY(1rem);
}

@media (max-width: 900px) {
  .site-header__nav,
  .header__nav { display: none; }
  .header__actions .btn--primary { display: none; }
  .site-header__menu-btn,
  .menu-btn { display: flex; }
  .theme-toggle--header { display: none; }
}

@media (max-width: 540px) {
  .site-header__logo-text {
    display: none;
  }

  .site-header,
  .header {
    padding-block: 1rem;
  }
}