/* ヘッダースタイル */
.site-header {
  background-color: var(--white);
  box-shadow: var(--box-shadow);
  position: sticky;
  top: 0;
  z-index: 1000;
  transition: var(--transition);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0;
}

/* ロゴ */
.site-logo {
  max-width: 76vw;
  flex-shrink: 0;
}

.logo-link {
  display: flex;
  align-items: center;
  text-decoration: none;
  color: var(--text-color);
}

.logo-img {
  width: 50px;
  height: 50px;
  margin-right: 0.75rem;
}

.logo-text {
  display: flex;
  flex-direction: column;
}

.logo-name-zh {
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
  color: var(--primary-color);
  line-height: 1.2;
}

.logo-name-en {
  font-size: var(--font-size-sm);
  color: var(--text-light);
  line-height: 1.2;
}

/* ナビゲーション */
.main-navigation {
  display: none;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-link {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  color: var(--text-color);
  text-decoration: none;
  padding: 0.5rem 0;
  position: relative;
  transition: var(--transition);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--primary-color);
  transition: width 0.3s ease;
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-link:hover {
  color: var(--primary-color);
}

/* モバイルメニュートグル */
.mobile-menu-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  margin-left: 2vw;
}

.hamburger-line {
  width: 24px;
  height: 2px;
  background-color: var(--text-color);
  margin: 2px 0;
  transition: var(--transition);
}

.mobile-menu-toggle.active .hamburger-line:nth-child(1) {
  transform: rotate(45deg) translate(5px, 2px);
}

.mobile-menu-toggle.active .hamburger-line:nth-child(2) {
  opacity: 0;
}

.mobile-menu-toggle.active .hamburger-line:nth-child(3) {
  transform: rotate(-45deg) translate(7px, -4px);
}

/* モバイルナビゲーション */
.mobile-navigation {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background-color: var(--white);
  box-shadow: var(--box-shadow-lg);
  border-top: 1px solid var(--border-color);
}

.mobile-navigation.active {
  display: block;
}

.mobile-nav-menu {
  padding: 1rem 0;
}

.mobile-nav-item {
  border-bottom: 1px solid var(--border-color);
}

.mobile-nav-item:last-child {
  border-bottom: none;
}

.mobile-nav-link {
  display: block;
  padding: 1rem 1rem;
  color: var(--text-color);
  font-weight: var(--font-weight-medium);
  text-decoration: none;
  transition: var(--transition);
}

.mobile-nav-link:hover {
  background-color: var(--background-light);
  color: var(--primary-color);
}

/* タブレット以上 */
@media (min-width: 768px) {
  .main-navigation {
    display: block;
  }

  .mobile-menu-toggle {
    display: none;
  }

  .logo-img {
    width: 60px;
    height: 60px;
    margin-right: 1rem;
  }

  .logo-name-zh {
    font-size: var(--font-size-xl);
  }

  .logo-name-en {
    font-size: var(--font-size-base);
  }
}

/* デスクトップ */
@media (min-width: 1024px) {
  .header-content {
    padding: 1.5rem 0;
  }

  .nav-menu {
    gap: 3rem;
  }

  .nav-link {
    font-size: var(--font-size-lg);
  }
}