#site-header {
  position: fixed ;
  top: -64px;
  left: 0;
  width: 100%;
  height: 64px;
  background: rgba(252,252,252, 0); /* 初期透明 */
  z-index: var(--z-header);
  padding: 0 40px;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: none;
  transition: top 0.4s ease, opacity 0.4s ease, background 0.3s ease;
}

#site-header.active {
  top: 0;
}

#site-header.scrolled {
  background: #fcfcfc !important;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

#site-header.hide-header {
  transform: translateY(-100%);
  opacity: 0;
  pointer-events: none;
}

#header-logo {
  height: 40px;
  opacity: 0;
  visibility: hidden;
  transition: opacity 1.0s ease, visibility 1.0s ease;
}

#header-logo.visible {
  opacity: 1;
  visibility: visible;
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.header-contact-btn {
  padding: 0.6em 1.2em;
  border-radius: 6px;
  background: #007acc;
  color: #fff;
  font-weight: bold;
  text-decoration: none;
  transition: 0.3s;
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
}

.header-contact-btn:hover {
  background: #005fa3;
}

.hamburger-menu {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1.6rem;
  color: #333;
  padding: 0.4em;
}
.menu-label {
  font-size: 0.7rem;
  font-weight: bold;
  letter-spacing: 0.05em;
  color: #333;
}

.floating-scroll-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: #444;
  color: #fff;
  display: none;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  z-index: var(--z-topmost);
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
  transition: background 0.3s, transform 0.2s;
}

.floating-scroll-top:hover {
  background: #222;
  transform: translateY(-2px);
}

.floating-scroll-top.show {
  display: flex;
}

@media (max-width: 768px) {
  #site-header {
    padding: 0 20px;
  }

  #header-logo {
    height: 30px;
  }

  .header-contact-btn {
    padding: 6px 12px;
    font-size: 0.9rem;
  }

  .floating-scroll-top {
    width: 40px;
    height: 40px;
    font-size: 1rem;
  }

  .header-actions {
    gap: 12px;
  }
}

.floating-scroll-top {
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
}

.floating-scroll-top.show {
  opacity: 1;
  pointer-events: auto;
}

/* ▼ ハンバーガーメニュー用ドロップダウン（CSSのみ） */
.hamburger-wrapper {
  position: relative;
  display: inline-block;
  z-index: var(--z-menu);
}

#menu-toggle:checked ~ .dropdown-menu {
  display: block;
}

#site-header .hamburger-menu {
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  background: none;
  border: none;
  font-size: 1rem;
}

#site-header .dropdown-menu {
  display: none;
  position: absolute;
  top: 110%;
  right: 0;
  background-color: #fff;
  border: 1px solid #ccc;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
  min-width: 160px;
  border-radius: 6px;
  overflow: hidden;
}

#site-header .hamburger-wrapper .dropdown-menu ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

#site-header .hamburger-wrapper .dropdown-menu li {
  border-bottom: 1px solid #eee;
}

#site-header .hamburger-wrapper .dropdown-menu li:last-child {
  border-bottom: none;
}

#site-header .hamburger-wrapper .dropdown-menu a {
  display: block;
  padding: 10px 16px;
  color: #333;
  text-decoration: none;
  font-size: 0.95rem;
  transition: background 0.3s ease;
}

#site-header .hamburger-wrapper .dropdown-menu a:hover {
  background-color: #f0f0f0;
}