/* ============================================================
   HEADER — Transparent → White on scroll
   ============================================================ */

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-header);
  background: #FFFFFF;
  backdrop-filter: none;
  -webkit-backdrop-filter: none;
  transition:
    background 0.5s var(--ease-smooth),
    backdrop-filter 0.5s,
    box-shadow 0.5s;
}

/* Scrolled state */
.header.is-scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  box-shadow: 0 1px 0 rgba(0, 0, 0, 0.06);
}

/* ---- Inner layout ---- */
.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--s-header-h);
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 var(--s-gutter);
}

/* ---- Logo ---- */
.header__logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.header__logo-img {
  height: 28px;
  width: auto;
  transition: opacity 0.3s;
}

/* Dark logo default, light logo hidden */
.header__logo-img--dark {
  display: block;
}

.header__logo-img--light {
  display: none;
}

/* ---- Navigation ---- */
.header__nav {
  display: flex;
  align-items: center;
  gap: 36px;
}

.header__nav-list {
  display: flex;
  align-items: center;
  gap: 36px;
}

.header__nav-link {
  font-size: 13px;
  font-weight: 500;
  color: var(--c-text);
  letter-spacing: 0.02em;
  transition: color 0.3s;
  position: relative;
}

.header__nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: var(--c-orange);
  transition: width 0.3s var(--ease-out);
}

.header__nav-link:hover {
  color: var(--c-orange);
}

.header__nav-link:hover::after {
  width: 100%;
}

/* ---- CTA Button ---- */
.header__cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
  background: var(--c-orange);
  color: var(--c-bg);
  letter-spacing: 0.02em;
  transition: all 0.3s var(--ease-out);
}

.header__cta:hover {
  background: var(--c-orange-deep);
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(232, 103, 42, 0.2);
}

.header__cta i {
  font-size: 10px;
  transition: transform 0.3s var(--ease-out);
}

.header__cta:hover i {
  transform: translateX(3px);
}

/* ---- Hamburger ---- */
.header__hamburger {
  display: none;
  flex-direction: column;
  gap: 6px;
  padding: 8px;
  z-index: calc(var(--z-header) + 1);
}

.header__hamburger span {
  width: 24px;
  height: 2px;
  background: var(--c-text);
  transition: transform 0.3s, opacity 0.3s;
  display: block;
}

/* Hamburger active state */
.header__hamburger.is-active span:nth-child(1) {
  transform: translateY(8px) rotate(45deg);
}

.header__hamburger.is-active span:nth-child(2) {
  opacity: 0;
}

.header__hamburger.is-active span:nth-child(3) {
  transform: translateY(-8px) rotate(-45deg);
}

/* ---- Mobile Menu ---- */
.mobile-menu {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  z-index: var(--z-mobile-menu);
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 8px;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.4s, visibility 0.4s;
}

.mobile-menu.is-open {
  opacity: 1;
  visibility: visible;
}

.mobile-menu__list {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.mobile-menu__link {
  font-family: var(--f-heading-ja);
  font-size: 20px;
  font-weight: 500;
  color: var(--c-text);
  letter-spacing: 0.05em;
  padding: 12px 24px;
  transition: color 0.3s;
}

.mobile-menu__link:hover {
  color: var(--c-orange);
}

.mobile-menu__link--cta {
  margin-top: 16px;
  padding: 14px 40px;
  background: var(--c-orange);
  color: var(--c-bg);
  border-radius: 8px;
  font-family: var(--f-body);
  font-size: 15px;
}

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .header__nav {
    display: none;
  }

  .header__hamburger {
    display: flex;
  }

  .mobile-menu {
    display: flex;
  }
}