:root {
  --color_primary: #1a1a1a;
  --color_primary_light: #f0f0f0;
  --color_text: #111827;
  --color_text_muted: #6b7280;
  --color_border: #e0e0e0;
  --color_bg: #fafafa;
  --color_surface: #ffffff;
  --r-md: 10px;
  --r-lg: 14px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Yu Gothic", "Meiryo", "MS PGothic", sans-serif;
  background: var(--color_bg);
  color: var(--color_text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0 1.5rem;
  height: 56px;
  background: var(--color_surface);
  border-bottom: 1px solid var(--color_border);
}
.site-header .logo img {
  width: 130px;
  display: block;
}

.site-nav a {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--color_text);
  text-decoration: none;
  white-space: nowrap;
}
.site-nav a:hover {
  color: var(--color_primary);
  text-decoration: underline;
}
.site-nav a[aria-current=page] {
  color: var(--color_primary);
  text-decoration: underline;
  text-underline-offset: 0.25em;
}

.site-footer {
  text-align: center;
  padding: 2.5rem 1.5rem 3rem;
  background: var(--color_surface);
  border-top: 1px solid var(--color_border);
}
.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 0.5rem 1rem;
}
.site-footer__logo img {
  width: 150px;
  display: block;
}

.error-box {
  padding: 1rem 1.25rem;
  background: #fff0f0;
  color: #c0392b;
  border-left: 4px solid #e74c3c;
  border-radius: var(--r-md);
}