/* ==========================================================================
   Level Nexus — header.css
   Sticky header, desktop nav, mobile drawer, sticky mobile action bar.
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 249, 252, .88);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
  transition: box-shadow var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.site-header.is-stuck { box-shadow: var(--shadow-md); }

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

/* --- Brand -------------------------------------------------------------- */
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-3);
  /* The logo is 30px tall but the tap target must not be. */
  min-height: 44px;
  text-decoration: none;
  flex: none;
}

.brand img {
  height: 30px;
  width: auto;
}

@media (min-width: 900px) { .brand img { height: 38px; } }

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

@media (min-width: 900px) {
  .nav {
    display: flex;
    align-items: center;
    gap: var(--sp-2);
  }

  .nav__list {
    display: flex;
    align-items: center;
    gap: var(--sp-1);
    list-style: none;
    margin: 0;
    padding: 0;
  }

  .nav__list li { margin: 0; }

  .nav__link {
    position: relative;
    display: block;
    padding: var(--sp-2) var(--sp-4);
    border-radius: var(--r-pill);
    font-size: var(--step--1);
    font-weight: 500;
    color: var(--grey-800);
    text-decoration: none;
    transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
  }

  .nav__link:hover { color: var(--navy); background: var(--grey-050); }

  .nav__link[aria-current="page"] {
    color: var(--navy);
    font-weight: 600;
  }

  .nav__link[aria-current="page"]::after {
    content: '';
    position: absolute;
    left: 50%;
    bottom: 2px;
    width: 16px;
    height: 2px;
    background: var(--teal);
    border-radius: 2px;
    transform: translateX(-50%);
  }

  .nav__cta { margin-left: var(--sp-3); }
}

/* --- Hamburger ---------------------------------------------------------- */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1.5px solid var(--border-strong);
  border-radius: var(--r-md);
  background: var(--white);
  color: var(--navy);
  flex: none;
}

.nav-toggle:hover { border-color: var(--navy); }

@media (min-width: 900px) { .nav-toggle { display: none; } }

.nav-toggle__bars {
  position: relative;
  width: 19px;
  height: 13px;
}

.nav-toggle__bars span {
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform var(--dur) var(--ease), opacity 140ms var(--ease), top var(--dur) var(--ease);
}

.nav-toggle__bars span:nth-child(1) { top: 0; }
.nav-toggle__bars span:nth-child(2) { top: 5.5px; }
.nav-toggle__bars span:nth-child(3) { top: 11px; }

.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(1) {
  top: 5.5px;
  transform: rotate(45deg);
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars span:nth-child(3) {
  top: 5.5px;
  transform: rotate(-45deg);
}

/* --- Mobile drawer ------------------------------------------------------ */
.mobile-nav {
  position: fixed;
  inset: var(--header-h) 0 0 0;
  z-index: 99;
  display: flex;
  flex-direction: column;
  background: var(--ink);
  color: var(--text-invert);
  padding: var(--sp-5) 0 calc(var(--sp-6) + var(--actionbar-h));
  overflow-y: auto;
  overscroll-behavior: contain;
  visibility: hidden;
  opacity: 0;
  transform: translateY(-10px);
  transition: opacity var(--dur) var(--ease),
              transform var(--dur) var(--ease),
              visibility 0s linear var(--dur);
}

.mobile-nav.is-open {
  visibility: visible;
  opacity: 1;
  transform: none;
  transition-delay: 0s;
}

@media (min-width: 900px) { .mobile-nav { display: none; } }

.mobile-nav__list {
  list-style: none;
  margin: 0 0 var(--sp-6);
  padding: 0;
}

.mobile-nav__list li {
  margin: 0;
  border-bottom: 1px solid rgba(234, 241, 251, .1);
}

.mobile-nav__link {
  display: flex;
  align-items: baseline;
  gap: var(--sp-4);
  padding: var(--sp-4) 0;
  font-family: var(--font-display);
  font-size: var(--step-2);
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--white);
  text-decoration: none;
  transition: color var(--dur) var(--ease), padding-left var(--dur) var(--ease);
}

.mobile-nav__link:hover,
.mobile-nav__link:focus-visible { color: var(--teal); padding-left: var(--sp-2); }

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

.mobile-nav__idx {
  font-family: var(--font-mono);
  font-size: var(--step--2);
  color: var(--navy-300);
  letter-spacing: .1em;
  flex: none;
}

.mobile-nav__link[aria-current="page"] .mobile-nav__idx { color: var(--teal); }

.mobile-nav__foot { margin-top: auto; }

.mobile-nav__contact {
  display: flex;
  align-items: center;
  min-height: 44px;
  font-family: var(--font-mono);
  font-size: var(--step--1);
  color: rgba(234, 241, 251, .7);
  text-decoration: none;
  padding: var(--sp-2) 0;
}

.mobile-nav__contact:hover { color: var(--teal); }

/* --- Sticky mobile action bar ------------------------------------------- */
.action-bar {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 98;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-3);
  padding-bottom: calc(var(--sp-2) + env(safe-area-inset-bottom, 0px));
  background: rgba(255, 255, 255, .95);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-top: 1px solid var(--border);
  box-shadow: 0 -4px 20px rgba(11, 31, 63, .07);
}

@media (min-width: 900px) { .action-bar { display: none; } }

.action-bar .btn {
  min-height: 44px;
  padding-inline: var(--sp-3);
  font-size: var(--step--1);
  font-weight: 600;
}

.action-bar .btn svg { width: 1.05em; height: 1.05em; }

/* WhatsApp brand green reads as the recognised action, not as brand palette */
.btn--whatsapp {
  background: #12833C;
  border-color: #12833C;
  color: var(--white);
}
.btn--whatsapp:hover { background: #0C6B30; border-color: #0C6B30; color: var(--white); }