:root {
  --bg: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --line: #e5e7eb;
  --soft: #f9fafb;
  --nav-height: 64px;
}

* { box-sizing: border-box; }

body { margin: 0; }

.site-header a,
footer a { text-decoration: none; }

.site-header .container {
  width: min(100% - 32px, 960px);
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  width: 100%;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  font-family: "Open Sans", "Segoe UI", "Helvetica Neue", "Noto Sans", Arial, sans-serif;
}

.nav-inner {
  min-height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex: 0 0 auto;
}

.home-button { display: inline-flex; align-items: center; flex: 0 0 auto; }
.logo-img { height: 48px; width: auto; display: block; }

.menu-button {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 8px;
  border: 0;
  border-radius: 999px;
  background: transparent;
  cursor: pointer;
}

.menu-button:hover { background: var(--soft); }
.menu-button img { width: 24px; height: 24px; display: block; }

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
  font-size: 14px;
  color: var(--muted);
}

.nav-links a {
  position: relative;
  color: var(--muted);
  padding: 8px 12px;
  border-radius: 999px;
}

.nav-links a:hover { color: var(--text); }

.nav-links a.user-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  padding: 0;
  border-radius: 50%;
}

.user-button img { width: 24px; height: 24px; display: block; border-radius: 50%; }
.user-placeholder { display: block; width: 24px; height: 24px; border-radius: 50%; background: #e5e7eb; }
.user-circle { display: inline-flex; align-items: center; justify-content: center; width: 24px; height: 24px; border-radius: 50%; background: #4285f4; color: #fff; font-size: 14px; font-weight: 700; }

footer {
  padding: 10px 20px;
  color: #555;
  font-family: "Open Sans", "Segoe UI", "Helvetica Neue", "Noto Sans", Arial, sans-serif;
  font-size: .95rem;
  background: transparent;
}

.footer-inner { display: flex; flex-direction: column; align-items: center; gap: 10px; text-align: center; }
.footer-links { display: flex; flex-wrap: wrap; justify-content: center; }
.footer-links a { margin-right: 15px; color: #007bff; line-height: 2; }
.footer-links a:hover { text-decoration: underline; }
.copyright { margin: 1rem 0 0; color: rgb(80, 80, 80); font-size: .90rem; }

@media (max-width: 640px) {
  :root { --nav-height: 72px; }
  .nav-inner { min-height: var(--nav-height); padding: 0; align-items: stretch; gap: 0; flex-direction: column; }
  .header-top { width: 100%; min-height: 72px; }
  .logo-img { height: 56px; }
  .menu-button { display: inline-flex; }
  .nav-links { display: none; width: 100%; padding: 12px 0 16px; gap: 0; flex-direction: column; align-items: stretch; font-size: 18px; line-height: 1.4; }
  .site-header.menu-open .nav-links { display: flex; }
  .nav-links a { display: flex; align-items: center; width: 100%; min-height: 48px; padding: 12px 16px; border-radius: 8px; background: transparent; }
  .nav-links a:hover { background: var(--soft); }
  .nav-links a.user-button { justify-content: flex-start; width: 100%; height: 48px; min-height: 48px; padding: 12px 16px; border-radius: 8px; }
}