/* ===== ヘッダー ===== */
.site-header {
  background: linear-gradient(to right, #eaf3fa, #d6e3ec);
  color: #2c3e50;
  text-align: center;
  padding: 0.6rem 1rem;
  border-bottom: 1px solid #ccdce5;
  box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.site-header h1 {
  margin: 0;
  font-size: 1.4rem;
}

.site-header h1 a {
  color: inherit;
  text-decoration: none;
  font-weight: 600;
}

.sub-copy {
  margin-top: 0.3rem;
  font-size: 0.75rem;
  color: #555;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* ===== ナビ ===== */
.header-nav-menu {
  list-style: none;
  display: flex;
  justify-content: center;
  gap: 6px;
  margin: 0;
  padding: 0;
}

.nav-btn {
  text-decoration: none;
  color: #2c3e50;
  background: #f2f7fa;
  padding: 8px 14px;
  border: 1px solid #10e642;
  border-radius: 6px;
  transition: 0.2s;
}
.nav-btn:hover {
  background: #d4e7f2;
  color: #1f4e79;
}

/* ===== レスポンシブ ===== */
@media (max-width: 600px) {
  .site-header { padding: 0.45rem 0.8rem; }
  .site-header h1 { font-size: clamp(1.05rem, 4.5vw, 1.25rem); }
  .header-nav-menu { flex-wrap: wrap; gap: 6px; }
  .nav-btn { font-size: 12px; padding: 6px 10px; }
}

@media (max-width: 360px) {
  .nav-btn { font-size: 11px; padding: 6px; }
  .header-nav-menu { gap: 4px; }
}